•300  i: 


.       .  LTOH 


Approved: 


V 

$LLT&f£***r~Izr- 


*•  \ 


- 


Contents 

I*      Introduction 

II  Acknowledgments 

III  Materials 

IV  Physiological  states 

1.  Rigidity  and  attachment 
a.  Persistence  for  -weeks 

2.  Locomotor 

3.  Resting  or  "active  unoriented"  state 

4.  Comparison  of  the  physiological  states  of  the  different 
species  studied* 

V.  Responses  of  a  single  tube  foot 
1*  Extension. 

a.  Conditions  of  extension 

b.  Direction  of  extension 

1.  Locomotor  starfish 

2.  Stationary  starfish 

3.  Rigid  starfish 
o*  Mechanism 

1.  Normal 

2*  In  isolated  tube  feet 

3*  Mechanical  curvature, 

4.  Physiological  inertia  or  lag 
2.  Attaching 

a*  Conditions 

1*  Physiological  state 
b.  Strength  of  attachment 
c»  Structures  involved  in  attaching 

1.  Attaching  reactions  of  isolated  tube  feet. 

728925 


d.  "Dependence  of  attaching  reaction  in  isolated  tub*  faet 

upon  physiological  state  of  organism, 
•.  Attaching  by  only  a  part  of  the  ambulacra!  disk, 
3*  Releasing  of  attahment  and  withdrawal 
a*  Result  of  stimulation  of  side  of  column* 
b.  Response   to  st&sulation  of  the  disk, 
o.  Detaching  and  withdrawal  of  isolated  tube  feet, 
d*  Detaching  and  withdrawal  as  a  response  to  physiological 

conditions  in  the  nervous  system* 
4*   The  step  reflex* 

iJjW* 

a.  Intergradations  with  drawing  response* 
1  Difference  in  extension 

2.  Difference  in  withdrawing* 

b.  Description  of  the  step  reflex 

0*   Significance  of  extension^  during  back  sweep* 

d*  Analysis  of  the  contact  stimulus  which  initiates  the 

step  reflex* 
•«  Analysis  of  the  factors  asrerning  the  orientation  of 

the  step  reflex* 

1*  Extension  determined  by  "physiological  an^terior*  of 
animal • 

2*  Lashing  back  determined  either 

a*  by  location  of  contact  stimulus  or 

b*   tho  condition  of  relative  excitability  of  the  different 

parts  of  the  longitudinal  musculature* 
§• statue  of  the  attaching  relfex  during  the  step  reflex  and  its 

modifications* 

g,  Delation  of  the  attaching  reflex  to  the  amount  of  resistance 
to   the  step* 
1*  Methods  of  studying* 
2,  Numerical  expression  of  this  relationship  Asterina  2*7 


Pycnopodia  2.06 

3*     This  is  no   expression  of  the  relative  attaching 

ability  of  these  animals  when  not  in  the   locoiaotor   state, 
h.    Strength  of  the  step  reflex  (pulling  ability) 

1.  Pulling  ability   in  Pi skater  ooraoeus 

2.  Pulling  ability  in  Ast 3rina.Miniata 

1.  On  a   solid   substrate  with  and  without  additional 
weight  on  its  dorsal  side. 

2.  On  sand  with  and  without   load 

3*     Pulling  ability  in  Pyonopodia  helianthoidas 

1.  On  said   substrate  with  and  without  load 

2.  on  sand  with  and  without  load. 

VI.  Coordination  of  the  tube  fast. 
1«  Preliminary  description 

2.  Coordination   in  the  tube  feet  of  the  rigid  starfish 

a.  Retraction 

b.  Extension 

c.  Nervous  mechanism 

3.  Coordination  in   the  gills 

a.  Ciliary  currents  in  gills. 

4.  Coordination  that  involves  some  orientation  of  the  tube  feet. 

a.  Coordination  to  attached  tube  foot  and  step  reflex. 

5.  Coordination  to  passive  movements  of  tube  feet. 

a*  After  twisting  tube  foot. 
6*  Coordination  of  the  tube  feet  in  active  starfish. 

4.  Tendency  of  each  arm  to  migrate  in  its  own  direction. 

VII.  Formation  of  the  unified  impulse* 

1.  General  statement  of  the  mechanism  of  the  positive  response 

2.  General  description  of  the  negative  response. 

3.  Detailed  description  of  positive  and  negative  responses  in 
Pyonopodia. 


4*  Orientation  as  a  result  of  stimulating  the  dermal  nei 
net,  or  a  general  stimulation  of  all   the  tube  feet* 

6*   The  significance  of   the  negative  behavior  of  the  isolated 

rays* 
VIII*  Behavior  of  the  starfish  when  under  the  influence  of  the 

unified  impulse 

1*  Positive  reaction  to  contact  and  other  stimuli* 
3*  Negative  reaction  to    contact  and  other  stimuli 
3.  Physical  as  distinguished  from  physiological  orientation* 
a.  Direct  orientation  of  the  tube  feet  of  the  leading  ray 

from  unilateral  stimulation, 
b*  Acceleration  cf  the  lateral  rays  by  stimulation  or  fy 

mechanical  factors* 

o*  Retardation  of  the  lateral  rays  by  stimulation  or  -^ 
mechanical  factors* 

XX*   General  oonsiderationof  coordination* 
1* 

General  consideration  of  the  factors  involved  in  governing 

the  direction  of  locomotion  in  the  starfish  and  their 
very  delicately  inter -related  balance* 
2*   Theories  of  the  mechanism  of  coordination* 
3*  Orientation  of  retracted   tube  feet  and  the  independence 
of  the  mechanism  of  orientation,   and  that  of  withdrawal 
or  stepping* 

X*   The  breaking  up  of  the  coordinated  impulse  into  areas  in  whio  h 
the  tube  feet  are  oriented  in  different  directions* 
1.   The  adaptiveness  of  this  response  as  illustrated  in 
a*  'Ihe  righting  reaction 
b*  The  teviation  reaction 

o*   '±he  locomotor  starfish  with  curved  lateral  arm* 
2*  Physiological  explanation  not  to  be  found  in  fcypothetioal 
"Complex  coordination  center". 


A 


3.     Possible  physiological  explanation  in   the  traction  on  the 
tube  feat  resulting  frora  the  movement  of  the  rays  over  th« 
substrata. 

a,  Application  of  this  to  Uangold*s  starfish,    to   the   right- 
ing  starfish  and   to    the  deviating   «tarfish. 

b.  Svidenoe  that  the  traction  of  the  substrate  does  orient 
the   tubo  feet. 

1.  Direct  evidence  inconclusive. 

2.  evidence  from  neurotoiaized  animals* 

5.  Evidence  from  the  behavior  of  the  animal  when  its  parts 

are  placed  on  separate   substrates. 
4*  Evidence   from   the  deviation  reaction. 

1.  Deviation  reaction  not  interfered  -.vith  by  cutting  nervous 
connections  *ith  int^r-radial  area. 

2.  Deviation  reaction  not  elicited  by  prodding  inter- 
red ial  area, 

3.  Quantitative  aspects  of  the  "deviation   rush*  with 
different  weights  on   the  animal  vary  irith  mechanical 
conditions  while  quantitative  aspects  of  stimuli  re- 
quired to   initiate   the  negative  reaction  do  not* 

4.  Operation  of  a  tendency  to   return  to  original  direction. 
XI.      Coordination  of  mov«3mants  of  the   tube  fe«t  with  those  of  the 

arm  as  a  whole* 
1*    Illustrations  of  the  tendency  of  an  arm  to  set  itself  more 

nearly  at  right  angles  to   its  actively  oriented  tubo  feet, 

when  such  movements  involve  dorsal   and  ventral   flexion  and 

lateral   twisting. 
2.   Ventral  flexion  of  ri£id,   of  injured,    and  of  nicotinized 

starfish* 


3,     :3esoripti.on  of  various  other  correlated  movement*  of 
the  tube  feet  and  arms* 

* 

4«     Description  of  th«  formation  of  the  coordinated  irapuliie 
•then  the  tuba  fset  ara  free  of  the  substrate* 

5*     Correlation  of  thaw  Movements  •with  the  righting  reaction, 
a*  Analyses  of  Jennings  seven  types  of  righting  reactions. 

6*  Description  of  th«  righting  reaction  as  it  occurs  vhan 
the  tube  feet  are  prevented  attaching  by  inverting  the 
animal  on  sand* 

XIX     Interpretation  of  the  righting  reaction  as  a  phase  of  loco* 
motion* 

1*      'Yidenae  from  the  movements  of  the  tube  feat  and  arms* 

£•     :*videnae  from  the  fact  that  stimulation  of  the  dorsal 

rnyodenaal  sheath  is  not  mn  essential  faotor  in  the  right- 
ing reaction, 

Z.      .Tidenoe  from  tlie  pereistsnoe  of  the  'unified  impulse* 
in  the  oam«  direction,   to  <*  degree  quantitatively  compar- 
able to  its  persistence  in  ordinary  loccuaotion 


IH3RODU3TIQH 

Although  the  behavior  and  physiology  of  starfish  and 
other  aohinoderas  have  been  given  the  attention  of  many  and  eminent 
naturalists,  it  was  hoped  that  an  intensive  study  of  the  problem  of 
coordination  in  the  several  speoies  available  would  bring  to  light 
some  data,  that  might  prove  of  interest  to  the  physiologist  and 
general  aoologist. 

The  work  was  commanded  in  the  autumn  of  1917,  but  in 
December  was  interrupted  by  fourteen  month*  s  service  in  the  army* 
Between  February  1919  and  June  1920  I  hive  spent  most  of  my  free 
time  experimenting  upon  and  observing  the  activities  of  starfish* 
It  would  be  quite  impossible  to  set  down  my  data  in  full,  following 
each  experiment  and  observation  out  in  detail,  for  reasons  of  space 
alone*  isy  evidence,  therefore,  has  undergone  a  rather  severe  select- 
ive process* 


I  wish  here  to  express  my  thanks  to  Professor  s,  J*  Holmes 
under  whose  direction  the  following  study  has  been  made,  for  his 
careful  criticism  and  his  many  helpful  suggestions*  I  am  greatly 
indebted  to  Professor  W*  K*  Fisher,  of  the  Hopkins  Marine  Station 
of  Stanford  University,  for  his  courtesy  in  putting  the  facilities  of 
his  laboratory  at  my  disposal,  and  for  bis  help  in  collecting  and 
keeping  alive  the  material.  He  was  also  kind  enough  to  detenoine  the 
speoies  I  worked  upon*  I  wish  also  to  express  my  thanks  to  Professors 
S.  S,  Maxwell  and  T.  0*  Burnett,  of  the  Physiology  department  of  the 
University  of  California  for  their  helpful  advice* 


-      »'At  fff 

,      .  «K>:-> 

viijwsii 


-2- 


To  ay  wife,  for  her  many  cheerful  sacrifices  and  her  will 
ing  help  in  numerous  ways,  is  due  my  fullest  gratitude* 


The  following  starfish  were  studied  intensively: 
Pi  ea,  star  oohraoaus   (Brandt) 

(Stimpsonj 


Asterina  miniata   (Brandt) 

Supplementary  observations  ware  made  on  the  following 
eohinoderms: 

I^ptasterias  eaualia   (Stimpson) 
Pisaster  bravigpinua   (Stiiapson) 
Bvagterias  troachelii    (Stirapson) 
Stromgrooentrotua  franoiaoamua  (Agassis  ) 
Professor  9*  K*  Fisher  writes  me  as  follows  "Jennings 
(1917)  worked  on  Asterias  aertulifera  Xantus*     I  hav«  the  actual 
specimen  sent,    for  identification  to   the  Museum  of  Comparative 
Zoology.     Verrill  calls  the  sane  species  Qrthasteriae  gonalena." 
Jennings  uses   the  name  Astarias  forreri  De  Loriol* 

So  far  as  X  am  aware,    the  above  seven  species  are   the  only 
Pacific  coast  starfish,  whose  physiology  has  been  described. 


BU»L»».-w-_*-*y  T  .«»-.T-^g??g        5*.  ^  *V  -JMHLO.  J* 

PWMM 

Piaster  ooraoeus,   was  collected  from  the  wharves  in 
Oakland  harbor  for  study  in  the  zoological  laboratory  of  the  Univer- 
sity of  California.     Jor  study  in  the  laboratory  of  the  Hopkins 
Marine  Station  they  were  obtained  from  the  surf  beaten  rooks  in 
front  of  the  building. 

A  remarkable  difference  was  evident  in  the  physiology 


--JUttS 


of  the  specimens  taken  from  those  tiro  locations,  which  was  not,    BO 
far  as  I  was  able  to  determine,   due  to  the  salinity  of  the    ;ater  in 
the  aquaria,   its   temperature,    freshness,   air  content  or  tha  food  needs 
of  the  animal * 

Pilaster     taken  from  the  surf -beaten  rooks  were  vary  inac- 
tive, would  attach  tightly  for  Ions  periods  of  time  to   the  substrate* 
and   could  not  be  exoitad  to   active  loooiaotion  by  the  most  varied,   per- 
sistent,  or  continued  stimulation*     The  water  in  the  aquaria  was  run- 
ning freely  and  would  keep  these  animals  alive  and  other  animals 
(  starfish,   crabs,    sea-urchins  etc.,)  alive  and  active  indefinitely* 

The  specimens  of  Pisaster  ooraoeua  taken  from  Oakland 
harbor  presented,  ^hen  fresh,   activity  of  an  almost  opposite  nature* 
It  was  quite  as  difficult  to  get  them  to   stop  crawling  as  it  was  to 
get  those  from  the  surf  beaten  rooks  to  start*     In  some  specimens  this 
state  of  extreme,  activity  never  appeared}  but  in  the  large  majority 
it  appeared  -7hen  the  animals  were  first  put  in  the  aquarium  and,   con- 
tinued,  interrupted  by  rest  periods  of  greater  or  less  extent,   for 
from  two  hours  to  two  months* 

The  only  speoiaen  from  the  surf -beaten  rooks  at  Pacific 
Grove  which  showod  this  marked  looomotor  activity  was  one  that  had 
been  in  the  quiet  water  of  tha  aquarium  for  nearly  thre«  weeks*     At 
the  end  of  this  period  the  animal  forsook  the  tight  clinging  which 
had  occupied  it  during  its  struggle  to  maintain  a  foot  hold  on  the 
rocks  and  began  active  migration* 

The  specimens  occurring  on  piles  in  the  relatively  quiet 
waters  of  Oakland  harbor  do  not  attach  very  tightly,   though  they  can 
do  so  when  disturbed  and  are  not  nearly  so  prone  to  attach  Then 
brought  to  the  aquarium* 

X  am  not  inclined  to  attribute  this  behavior  to  "learning" 


•4- 


(see  Sterne  1891}  nor  even  to  habit  formation   (Jennings  1907),   but 
would  explain  it  moro  simply  as  a  very  marked  and  striking  example 
of  "physiological  inertia" t : (Jennings  1907)  or  tha  tendency  to 
tontinue  past  responses  in  spite  of  present  stimulations,     v/e  shall 
inquire  further  into   the  nature  of  this  tendency,    (see  also  Romanes 
&  Swart   (1881),  Prayer   (1886),  Mangold   (1908^)f   Bonn   (1908),    Oowles 
(1911   ),  Holmes   (1911),    lole   (19150). 

To  the  tto  physiological  states  above  noted,    the  one  of 
extreme  rigidity  and  attachment  and  the  other  of  aotivs  locomotion 
with  the  arms  more  or  less  extend  ad  and  flexible  w«  may  add  a  third 
state  in  -vhich  the  arms  are  eat  tended  as  in  the  loooootor  st^te  but 
the  tube  foot  are  not  oriented  in  any  particular  direction  as  they 
•are  in  the  locomotor  aninal.     The  tube  feet  are  more  or  less  aotiye 
and  not  tightly  attached. 

Aniaals  in  these  three  states  will  be  referred  to  as 
(l)   lodoiaotor  or  crawling  starfish,    (2)  rigid  starfish  and  (3)  active 
but  unoriantodjOr  resting  starfish  respectively*     In  these  different 
states  the  animal's  behavior  is  wholly  different* 

Pyonopodia  heliao trifles  the  large  20  rayed  "sun  star* 
present  these  same  physiological  ststes  in  quite  as  marked  a  manner 
as  Pisagt-sr.     I  hive  nevar  observed  pyonooodia  to  assua»  the  rigid 
or  attached  state  fhen  on  a  horizontal  substrate*     It  will  attach 
quite  readily  to  a  vertical  substrate,  and  with  such  tenacity  that 
it  is  very  difficult  to  rajaove  it,   but  on  a  horizontal  substrata  I 
have  observed  it 


-5- 

only  in  the  looomoto^or  resting  (active  but  unoriented) 
state. 

In  Asterini   the  physio  logical   states  are  not  wall 
differentiated.     The  animal  dees  not  attach  tightly  though 
it  does  become  rather  rigid  and  inactive.      ±he  looomotor 

^,yV>XwW 

state  is  olearp^lthouEh  in   the  unoriented  state  one  often 

tb 
sees  the  snimil  make  lurches,   as  if  4&e  orawl  in  this  and   then 

in  that  direction  without  actually  doing  so* 

The  other  starfish  observed  seem  to  present  different 

physiclp  ioal   states  .-uore  or  less  analogous  to  those  described 

for  Pisaater. 

In  the  folio-fine  pages  we  shall  discuss  the  responses 

of  the  tube  feet  as  individual  organs,    their  coordination 

among  themselves,   and  the  relation  of  these  movements  to  the 

c.-ordinition  of  locomotion  and  righting* 

ft*  4  sipofrg  xuas  POOT 


The  tube  foot  of  a  nomnl  starfish  may  exhibit  the  follow* 
ing  responses,    •.tiich  vary,  as  we  sJnll  see,  with  the  physio* 
logical   state  of  the  aniaal:    (1)  extenaion;(2)  attaohing(S) 
withdrawal,  (4)  step  reflex* 

3HTBHSION 


-Extension  of  the  tube  feet  is  best  seen  in  the  active 
starfish  upon  the  absence  of  those  mtimulations  which  normally 
cause  a  withdrawal  of  the  tube  foot  or  complicate  its  extension 
by  inducing  the  activities  of  attaching  or  ""stepping." 

70  study  the  factors  which  govern  simple  extension  of  the 
tube  feet  it  is  necessary  then  to  invert  the  animal  on  its 
abofal  side,   or  better  yet  to   suspend  it  freely  in  the  water.     Thus 
are  avoided  the  disturbance  of  contact  stimulation. 


•6- 

Direotipn  oj[  extension 

The  extension  is  conditioned  in  direction  by  the  looomotor 
activity  of  the  animal  as  a  whole.     If  the  starfish  is/  uigra  ting 
in  the  direction     f  a  certain  arm,    for  instance,    the  tube  feet 
will,   in  the  absence  of  contact  stimulation  extend  themselves 
in  this  direction,   and  remain  so   extended  until  stimulated 
either  to  retract  or  execute  the  step  reflex. 

In  the  stationary,   non-rigid  starfish  the  tube  feet  of 
the  outer  part  of  the  ray  are,   in  the  absence  of  contact  simulation, 
extended  more  or  less  toward  the  tip  of  the  ray  and  ant  moving 
(•feeling")  about  in   that  direction*         This  of  course  is  not 
constant  and  is  laost  noticeable  in  the  most  active  specimens. 

Starfish  that  are  inactive  or  in  the  rigid  state  do  not 
extend   the  tube  feet  as  much  as  do  individuals  of  the  active 
non-loooaotor  type.     Vhe  most  noticeable  difference  between  the 
behavior  of  the  tafcaartocxxocfxtloi  tube  feet  of  such  a  starfish 

and   those  of  a  normally  active  one  is  that  the  former  are  not 

avy«y 
directed  <n*t  from  the   tips  of  the  rays*      They  may  be  waving 

about  approximately  at  right  angles  to  the  ray  or  even  direc- 
ted somewhat  toward   the  center. 


The  mechanism  of  extension,    first  described  by  Heamur 
(1910)   in  a  very  interesting  paper  is  well  known.     It  involves 
a  contraction  of  the  aabulacral  ampulla  and  a  relaxation  of  the 
longitudinal  musculature  of  the   tube  foot*     To  ascertain  the 
dependence  of  this  relaxation  of  the  longitudinal  musculature 
on  the  radial  nervous  system,    tube  fe  ;t  were  cut  off  and  tied 
on  to   the  end  of  a  capillary  glass  tube*     This  was  connected  with 
a  column  of  sea  -water  arranged  so   that  the  pressure  could  be 


•7- 


i  nor  eased  or  decreased  by  raising  or  lowering  a  reservoir,  which 
was  connected    to   the  capillary  tube  by  a  lon&  rubber   tube* 
If  the  tube  feet  were  injected  with  water  at  a  pressure  of 
10  cm   (HgO)    they  would   slowly  extend  in  the  absence  of  contact 
stimulation  but  not  to  their   .vhola  normal  length*     The  extension 
•was  much  slower  than  the  active  extension  of  a  norraal  tube 
foot  and  not  so  complete.      If  caused   to  contract  and  then 
injected  *»ith  a  pressure  of  more  than  2  ra  (HgO)  the  extension 
was  not  appreciably  accelerated  but  could  be  made  more  complete* 

Tube  feet  anaesthetized  in  Kg  SOA  would  extend  completely  under 

* 

low  pressures.     This  anaesthetization  involved/  also  relaxation 
of  the  circular  muscles  so   tint  the  tube  foot  presented  a 
noticeably  greater  diameter  than  the  normal  tube  foot*     In  the 
extended  as  well  as   the  contracted   tube  feet  there  was  a  quite 

constant  curvature  in  the  direction  of  a  clear  longitudinal 

<3l0n<?11ze  side 
Line  up-^hrr-sfe»£t  of  the  pedicel  which  I  take  to  be  the 


pseudohaemal  canal  (Ouenot  1888)  This  curvature  persists  in 
the  anaesthetized  (or  dead)  pedicel  and  is  therefore  probably 
due  to  mechanical  rather  than  to  physiological  factors* 

Active  tube  foot  preparations  were  allowed  to  extend  and 
assume   their  normal  curvature  toward   the  pseudohaemal  canal, 
and   then  were  bent  slowly  and  gently  in  some  other  direction. 
They  showed  a   tendency  to  remain  bent  in  that  direction  and 
then  slowly  to  bend  back  to   the  original     curvature*       An 

anaesthetized  or  a  dead   tube  foot  does  not  show  this  behavior* 

c, 
It  is  hense  physiological  in  its  nature  and  is  perhaps 

analagous  to   the  behavior  of  a  aea-urohin's  spine  when  bent 
over  to  one  side/    (Yon  Uexku«ll  1900   )• 

Attaching 

Attaching  is  conditioned  by  the  physiological   state  of 


•8- 

the  organ!  am*  The  tube  feet  of  Pisastar  in  ordinary  looomotion  do 
not  attach  very  strongly*  ./hen  in  the  rigid  appressed  stAte,  how* 
ever,  they  are  ao  tightly  adherent  that  many  may  be  pulled  off  be* 
fore  the  animal  can  be  removed  from  the  substrate. 

Strength  ojg  attachment* 

Mr.  '.Vaymouth  of  the  physiological  department  of  Stanford 
University  informs  me  that  he  haa  released  the  tube  feet  of  suoh 
a  starfish  one  by  one  with  a  needle  until  there  were  just  enough 
tube  feet  adhering  to   suspend  the  Animal  from  the  lover  surface  of 
a  glass  plate*     The  estimated  area  of  the  disks  of  these  tube  feet 
multiplied  by  atoosphoric  praasure  was  approximately  equal   to  the 
weight  of  the  starfish  thus  snoring  that  these  organs  are  mechani- 
cally quite  efficient. 

^Structures  involved  in.  attaching. 

Attaching  is  a  reflex  *hioh,    though  it  may  be  modified 
by  outside  factors,    involves  neoossarily  only  the  muscular  and 
narvous  structures  of  the  pedicel. 

Tube  foot  preparations  texre  made  as  above  from  actively 


attaching  starfish,   great  oare  being  exercised  to  quickly  and 

A 

gently.     It  *as  found  upon  placing  suoh  a  tube  foot  against  a  stub- 
strate  that  in  about  five  oases  out  of  ten,   it  would  attach  and  hold 
against  considerable  tension   (in  one  case  enough  to   tear  off  a 
part  of  the  disk).     This  po^er  of  attaching  was  lost  after  a  few 
trials. 

.o..f  attachin     roaotiQn  jn  iaolatsd  tube  feet 


upon  i^iyaiologioal  .state  o.f 

Tube  foot  preparations  were  also  made  from  starfishes  that 
were  not  attaching   (in  active  looomotion,    feeling  about  the  surface 
film,   etc.)     These  did  not  attach. 


•9- 

The  interpretation  of  this  phenomenon  is  rather  difficult. 
It  is  well  known  that  when  aa  attached  starfish  la  pulled  off  from 
its  substrate,   many  of  the  tube  feet  will  be  torn  off  and  may  remain 
attached  to  the  substrate  for  some  time*     The  experiment  shows  fur* 
ther  that  mioh  a   tube  foot  nay  reattaoh  even  tho  it  be  unconnected  with 
the  radial  nervous  system   (sea  also  Botazzi  1898  and  Ruaso  1913)* 

It  is  well  Vnown,   also,    that  some  times  a  a  starfish  is  very 

\ 

prone  to  attach  its   tube  feet  tightly  to  the  substrate  while  at  other 
times  the  animal's  energy  is  taken  up  with  loooiaotion  or  some  other 
activity  that  does  not  entail   tight  attachment  of  the  tube  feet 
(Jennings  1907)*     The  experiment  shows  also   that  there  is  a  difference 
in  the  behavior  of  the  isolated  tube  feet  which  corresponds  to   the 
fluctuation  of  the  attaching  reaction  of  an  animal  from  time  to   time* 

According  to   Von  Uexkull,    the  contraction  of  a  muscle  is 
due  to  "Tonuft*  which  is  metaphorically  referred  to  as  a  fluid,   that  is 
carried  to   the  muscle  through  the  nerves*     Furthermore   (1903)  by  out* 
ting  the  nerve  which  has  supplied   this  tonus,    the  "fluid*  may  be  en- 
trapped in  the  muscle,   and  the  muscle  remain  contracted*      Vhile  this 

(t^»n^e4d  i<*0*lr) 

theory  has  not  been  vory  widely  accepted,  some  of  its  aspects  are 

/\ 

partly  congruent   vith  the  behavior  of  isolated  tube  feet* 

Tube  foot  preparations,   however,   that  are  capable  of 
attachment  do  not  present  any  differences  in  appearance  from  those 
that  are  not  capable  of  attachment*     Thus  they  are  not  influenced 
by  entrapped  " tonus*   in  the  sense  of  Von  Uexkull  because  "tonus" 
elicits  contraction  or  tension  in  the  muscles  it  affects  and  the 
tube  feet  undjr  observation  did  not  seem  to  differ  in  this  respect 
from  tube  feet  which  would  not  attach  to  a  substrate*     In  fact  they 
differed  from  tube  feet  taken  from  a  starfish  in  active  locomotion 
only  in  being  in  such  a  state  of  physiological  activity  that  the 


* 


01 


-10- 


attaohing  reflex  la  the  one  t/iut  contact  stimulation  alioita. 

It  -would  seem,    then,    from  the  difference  in  behavior  of 
tube  feet  taken  from  animals  in  different  physiological  atatea  that 
this  etato  of  specialized  irritability  ia  a  condition  of  the  ambu- 
lacral    Us^  and  ^hilo  angendarsd,   most  probably,   by  influences  pro- 
ceeding fro^a  the  radial  nervoua  ayatam,   is  not  dependent  upon  that 
aystea  for  a   rather  limited  continuance, 

Attaching  bjc,  only  a,  P-^  rt  g^  ifce  aabuliorapl  digl:t 
The  :».tt-x9hing  raflex  does  not,  naoessarily  involve  all  of 
the  ambul-5or«l  disk,      rh.e  and  of  a  gnall  rod  was  placed  on  various 
partn  of   tii3  lo'tar  surface  of  a  larsa  actively  attatiiiing  pedio«l» 
The  part  in  cont-act  -7ith  the  end  of  t>io  rod  attached  with  aroat  force, 
auoh  thit  :in  atteispt  to  withdraw  the  rod  result M  in  pulling  a  portion 
of  th;j  disk  out  of  shape.     A  fina  hook  *»a  laid  flat  against  the 


of  tub3   r          -j   thit 

atroaiant  ^*5.9  hoo.V-ahaj 


* 


iak  in  contact    *.ith  the  in- 
attached  to  the  hook  quite 


strongly*     In  fact,   any  part  of  varioua  di*kf  ^faa  found  to  attach 
even  to  the  point  of  a  nesdls,   •-•shan  tM»  was  applied  gently  enough. 
Thea«  exparimanta  were  repeated  upon  Isolated  tube  foot  preparat-iona 
vith.  the  same  result. 

Tha  disk  as  an  attacliing  laeehaniara,    than,   «ioea  not  act  as 
a  whole  (Preyer  1086),  but  rather  the  inaupping  oooura  to'vard  the 
center  of  any  properly  stimulated  ai-ea. 


Re\ea  a  ing  and^  •vitSidraval   -*s  a   result  of  8tL.iiaul  xticm  o/ 
p,ide  p^*  colxam« 

Rele&ae  of  attaclunant  and  withdrawal  are  V«o  reaponeee 


•11- 


that  are  closely  analagous*     If  a  starfish  IB  tipjhtly  attached 
to  the  side  of  the  aquarium,    to  gat  it  off  without  injury  to  the 
tube  fget,   one  has  but  to   stimulate   the   aides  of  the  tube  feet  sharply 
Trith   the  eds*  of  seme  flat  instrument  that  will   slip  undor  the  star- 
fieh,     This  stimulation  causes  the  release  of  the  stimulated  tube  feet 
and  sometimes  the  release  of  neighboring  tube  feat* 

If  a  starfish  be  inverted  or  suspended,   when  not  exhibit- 
ing a  locomotor  tendency,    and  the  side  of  an  extended  tube  foot  be 
touched  even  v-jry  lightly,    thire  ie  an  iflwoediate  collapse  and  with* 
draval  of  UXQ  tube  foot*      Careful  obpervation  of  the  phenomenon 
leads  one  to   think  that  it  is  a  reeult,    first  of  the  relaxation  of 
the  ampulla  and  second  of  a  contraction  of  the  longitudinal  muscula- 
ture of  the  tube  foot* 

aif  a,  ra8»onq«9  J^o.  glj^ulAtion  o_f. 


If  the  tube  feet  show  a  t'aidency  neither  to  locomotion  nor 
to  «ttaohraent,  this  same  withdrawal  reaction  follows  the  «tianilation 
of  the  diaV. 

Usually,  ho-vorer,    Uiere  is  a  tendency  toward  attachment 
which  does  not  necessarily  interfere  with  th»  presence  of  the  with- 
drawing reaction*     This  conclusion  was  reached  from  a  study  of  the 
reactions  of  tube  feet  to  very  light  suspended  objects*     A  small 
piece  of  thin  celluloid,    suspended  by  a  thread,  was  brought  in  con- 
tact with  extended   (non-locomotor)   tuba  feet*     The  first  response* 
usually  was  found  to  be  attachment*     After  tide,  dap  ending  on  con- 
ditions which  will  be 


till 


•12- 

discussed  in  connection   »ith  the  step  reflex,  a 
extension  sometimes  occurred  due  probably  to  an  increased 
tension  of  the  ampullar  muscles.     Next/  in  sequence  in  the 
non-loco  -otor  tube  feat  was  the  retraction  of  the  tube  foot 
and  a  consequent  mo  Ting  of  the  piece  of  celluloid  toward 
the  ray*     Thin  does  not  involve  release  of  the  substrate  by 
the  disc  as  does  the  withdrawing  on  stimulation  of  the  side 
of  the  column  yind  is  probably  the  response  of  the  tube  feet 
t  *t  is  involved  when  the  ani.rul  shrinks^  down  on  the  substrate 
after  having  b»en  disturbed* 

and  wi  thdra'»al  oj;  isolated   tubft 


An  isolated  tube  foot  preparation  does  not  show  typical 
withdrawal  reactions,   because  of  course,    the  reciprocal  action 
of  the  ampulla  is  absent*     Harsh  stimulation  of  the  column  of 
the  attached  tube  foot  preparation  was  fount  to  cause  release* 
Shortening  by  a  slow  contraction  of  the  longitudinal 
nusculnture  was  found  to  follow  sever*  stimulation  «f  any  part 
of  the  tube  foot,   even  against  a  strong  water  pressure  , 

Response  jfco  internal  changes 

Release  and  withdrawal  nc  of  attached  tube  feet  may  occur 
as  a  response  to  a  change  of  internal  physiological  conditions* 
Thus  tin  animal  all  of  whose  feet  were  tightly  attached,   one 
minute,  may  the  next  minute  be  seen  in  active  locomotion  about 
the  aquarium*     The  factors  governing  this  response  will  be 
taken  up  elsewhere* 


with  withdrawing  reaponsa* 


The  step  reflex  *  is  I  think,   merely  a  notification  of 

The  first  description  that  •  "l  can  find  o'^1  the*step«refiex*" 
is  that  Given  by  Reamur  &71CJ,     After  describing  the  morpho- 
logical  connection  of  the  ampullae   ("tiny  pearl  like*  balls')  and 
the  "legs"   (tube  feat?  he  goes  on  to  say  "But  one  brings  out 
the  whole  ingenious  mechanism  of  it  when  one  presses  the   finger 
on  one  of  the  MMlls**^        It  is  seen  to  empty  and  at  the   same 


•    •:     " 


-US- 
time,    the   'leg*  which  corresponds  to  it  becomes  inflated  and  elonga- 
ted,    Finally  it  is  aeon  that  on  cessation  of  the  pressure  the  ball* 
refill  and  the  legs  become  empty  and  shorten  themselves,   and  it  is 
nothing  more  than  this  that   the  starfish  does  in  extending  its  lega- 
to press  upon  the  balls,   aa  one  may  do  at  any  time  --vith  his  fingsr* 
It  is  easy  to  imagine  a   thousand  ways  in  which  the  starfish  can  do 
this.     The  compressed  balls  discharge  their  -tater  into   the  legs  which 
they  inflate  and   thus  extend,   but  when   the  starfish  ceases  to  press 
on  the  balls,    the  natural  elasticity  of  the  legs,   -*hlch  is  consider* 
able  causes  them  to  shorten*     These  legs,    thus  elongated  the  animal 
uses  in  locomotion  by  t*.****^  extending   them  out  toward  the  body  to 
which  traa  animal  wishes  to  move  and  attaching  to  it  at  a  vary  acute 
angle*     The  strength  -vith  which  the  leg  remains  affixed   to   this  body 
while   trying  to  make  a  right  angle  -sith  this   same  surface  obligee 
the  animal  to  approach*" 

of  the  withdrawing  reflex  as  a  responsa  to  contact  stimulation  of 
the  disk*     The  intargrading   steps  depend  upon  the  presence  to  a 
greater  or  less  degree  of  a  looozcotor  tendency*     This  expresses  it- 
self,   in  the  inverted  or  suspended  starfish,   as  already  shown  by  an 
orientation  of  the  extended  tube  feet  in  the  direction  of  the  phys- 
iological anterior*     If  the  locouotor  impulse  is  not  very  strong, 
the  only  modification  perhaps  that  will  toe  observable  in  the  with- 
drawing reaction,  will  be  an  exaggeration  of  the  tendency  to  extend 
after  the  contact  stimulation  and  before  the  withdrawal* 

With  the  increase  of  the  locomotor  impulse  comes  a  change 
in  the  behavior  of  the  tube  foot  wMoh  integrates  both  with  the  with- 
drawing response  and  the  step  reflex*     this  change  is  a  further  in* 
crease  in  the  above  noted  tendency  to  extend,  caused  no  doubt  by  an 
increase  in  the  tension  of  the  ampullar  muscles*     This  complicates 
the  withdrawing  action,   and  then  results,   for  reasons  which  we  will 
take  up   later  a  more  rapid  contraction  of  the  muscles  on  one  side  of 
the  pedicel  than  on  the  other*     This  gives  rise   to  a  lateral  movement 
of  the  tube  foot  'thich  increases  in  extent  with  the  increase  of  the 
locoraotor  impulse,    from  a  slight  bending   (fig*  3)  of  the  tube  foot 
to  one  side,    to  an  active  lashing  back  (fig*  4)  of  the  disk  with 
sufficient  force  to  throw  a  grain  of  sand  some  few  centimeters* 


.**  *e 


•13ft- 
Description  of  the  step  reflex. 

Under  ordinary  cireunstanoes  of  locomotion,    this  lateral 
•oreaeat  is   followed   by  retraction  and  toe  retraction  by  re*extenaion 
in   the  direction  of  locomotion.      This  infolres  contact  vith  the  sub- 
strata and   UM  itiaulations  -*hich  gire   rise   to   the  repetition  of  the 
lashing  baek,    the  retraction  and  the  re*«ztension«     These  aoTeaents 
•vhioh  inrolre,    as  sho-vn   in  detail  later,   attaohnent  to  tha  substrate, 
are  tl'x>se  of  ordinary  locomotion,     iadi  tube  foot,   acting  indepeadeat- 
ly  as   to   tiae  but  in  hansony  with  its  felloes  as   to  direction,   re* 
peats  these  ao Yemenis  as  long  as  contact  stiaculi  result  H  usi  extension 
and  the  locoaotor  iapulse  reaain  unimpaired* 


•14- 


Si  on 


pciri'v,:  . 


,*.  V        S  V""»p-W™ ' 

Jenr  >£*Tp.  90)   desori  *es   the  st«p  reflex  in 


torus  of  tha  behavior  of  a  tube  foot  on  a  solid  flat  substrate. 


i  >      5         4-         U7 

9  »ix»y>g<»»  4^«c«   {6*«ftbing  an  arc, 
as  it  does  IBM  stin*  obja  ,,  light  (See  also 

Ifameold  19084*     It  ia  this  tanftsmiy— oo-tieaaribe  an  arc,    to 
keap  fully  extended  as  the  disc  is  pushed  back,    that  koaps  the 
animal  veil  off  the  substrate  during  locomotion, 

A  further  analysis  of  the  step  reflex  raises   the  question? 


, 


-15* 

(1)  What  is  the  stimulus  which  sets  if  off?   (2)  what  factors 
govern  its  orientation?   (3)  What  is  the  Status  of  the 
attaching  reflex  in  the  various  stages  of  its  accomplishment. 
(4)  What  is  the  relative  strength  of  the  otep  reflex  in 
different  species* 

The  stimulus 

The  stimulus  which  sets  off  the  step  reflex  is  one  of 
gentle  contact  on  the  disc,  contact  on  the  column  or  harsh 
stimulation  of  the  disc  results  in  a  simple  withdrawal.     In 
absence  of  contact  stimulation,    there  is  no  approach  toward 
the  ste/p  reflex.     I  have  seen  a  large  ffyonopodia  on  its  back 
in  shallow  water,   remain  with  a  large  part  of  its  22,000 
(Verrill  1914)   tube  feet  extended  in  one  direction   (the  direc- 
tion changing  from  time  to  tine)   for  half  an  hour,  with 

'  wjP»      *  ^^r  i*f 

none  of  the  tube  feet  executing  the  step  reflex*     When,  however 
a  light  object,    tmch  «•  a  piece  of  celluloid  was  plaoed  on  the 
tube  feet  the  step  reflex  immediately  started  in  all  of  the 
tube  feet  receiving  the  contact  stimulation*     As  a  result  the 
piece  of  celluloid  was  quickly  "walked*   to   the  temporary 
posterior  of  the  starfish*     The  same  was  repeated  with  a  very 
thin  clear  glass  watch-crystal*  The  glass  could  not  be  seen 
at  all,   under  water,   but  its  course  across  the  tube  feet  could 
be  clearly  followed  by  observing  the  area  in  which  the  pedicels 
were  executing  the  step-reflex* 

Ihen  a  starfish  in  aotive  locomotion  is  brought  above 
the  surface  of  the  water  the  step  reflex  was  seen  to  occur 
without  further  stimulus*       An  aotive  specimen  of  Pyonopodia 
with  the  ventral  side  exposed  to  the  air,  presents 
the  likeness  of  some  strange  sort  of  military  activity.     «lth 
m*chin«f  like  regularity  the  22,000  bright  yellow  tube  feet 


-16 

ex  tend   themselves  out  toward  the  temporary  anterior  and 
then  lash  back  vigorously  in   the  opposite  direction,   exactly 
parallel  with  e-ich  other* 

The   true  significance  of  this  is  aean  if  the  tube  feet 
of  a  part  of  such  a  starfish  be  submerged.     Then  only  those 
tube  feet  that  touoh  the  surface  film  of  the  water,   or  those 
entirely  exposed   to  the  air  execute  the  step  reflem.     The 
submerged   tube  feet  remain  pointed  in  the  direction  of  the 
temporary  anterior  until  .some-  contact  stimulation,    from  the 
surface  film  or  from  some  solid  object  initiates  the 
step  refles. 

^hat  factors  govern  tiie  orientation  oJT  the,  step  reflex? 

The  first  phase  of  the  reaction,    the  extension  of  the 
tube  foot  is  a  function  of  the  physiological  orientation  of 
the  starfish*     This  will  be  analy  ed  further  elsewhere*     Now 
if  the  lashing  bac>  is  to  be  effective  in  locomotion,    it  must 
take  place   (as  it  does)   in  the  opposite  direction  from  the 
extension.     This, however,  merely  shows  that  the  response  is 
adaptive  and  is  not  a  physiological  explanation*     A  physiological 
explanation  may  be  looted  for  in  the  location  of  the  oontaot 
stimulation  on  the  disc  of  the  tube  foot  or  in  the  condition 
of  tension  in  the  musculature  of  the  column*     The  tube  foot 
as  it  extends  may  be  seen  often*  tho^not  always  *  to  touch 
the  substrate  first  with  the  poi^fMMtflfe*      *•*  miy  be 

X. 


expected   that  exitation  to  oonw^w.  „ _  ontaot 

stimulus  might  spread  to  the  side  of  the  column  1*3  and  cause 
its  contraction  more  quickly  than   to   the  side  2-4*     Furthermore 
a  contact  stimulus  at  the  place  2  does  not  elicit  the  step 


-17- 

reflex  with  as  much  readiness  and  regularity   (Pisaster)   as 
«  similar  stimulus  at  tho  place  1.        It  must  be  remembered 
however  that  in  normal  locomotion  the  diso  is  often  placed 
flat  on   the  substrate,  tid   that  when   the   tube  feet  are  exposed 
to   the  air  the  ourfaoo   tension  fil.-i  may  be  expected  to  oontnot 
with  equal  pressure  on  all  sides  of  the  disc,   and  thus  to 
stimulate   them  all  equally*     We  ha  TO  to  count  then  upon  the 
greater  excitability  of  the  muscles  on  the  side  1-3  in  the 
post-contact  phase  of  the  step  reflex*      This  is  comparable   to 
the  increased   tension  of  the  muscles  on  the  aide  2-4  in  the 
pro-contact  stage  of  the  step  reflex*     The  oscillations  of  the 
tube  feet  may  be  explained  in  terms  of  Von  Uexkiuflfs  law  of 
"tonus"   or  may  be  left  unexplained*     the  fact  is,  of  course 
that  they  move  back  and  forth  in  the  step-reflex  with  con- 
siderable regularity  and  precise  orientation*     The  factors  thai 
control  the  orient ition  of  the  animal  will  be  taken  up  in 
connection  with  an  analysis  of  coordination  aoong  the  tube  feet* 

Status  pjf  foe  attaohjlnf  reflex  during  the  stop  reflex* 

The  strength  of  attachment  during  the  atop  reflex  differs 
as  we  shall  see  with  the  different  species  and  with  the  amount 
of  resistance  there  is  to  the  accomplishment  of  the  step* 

In  general  wo  may  assume  from  observations  «n    ordinary 
locomotion  that  the  tendency  to  attach  is  strongest,   during  the 
progress  of  the  step  reflex.  Just  after  the  contact*     The 
tube  foot  usually  remains  attached  during  the  first  half  of  the 
backward  oscillation, but  the  likelihood  of  release   (or  slipping) 
is  found  gradually  to  onorease  during  tho  last  phase  of  the 
atep  reflex* 

A  largo  grain  of  sand  was  placed  on  one  of  the  ambulacra! 
disos  of  an  active  Pyonooodia.       The  step  reflex  which  resulted 
was  so  violent  that  tho  grain  of  sand  was  thrown  as  from  a 


-18- 

miniature  catapult,   a  distance  of  four  or  five  am.     on 
repeating  this,    the  elevation  or  "angle  of  fire*  was  aeen  to 
be  such  as  would  entail  release  of  the  grain  from  the  diao 
during  the  third  quarter  of  the  arc  that  the  diso  describes 
in  lashing  back.     Usually,  however,    in  disaster.  Asterina  etc., 
the  violence  of  the  lashing  back  is  not  so  sratt,   and   the 
release  is  not  very  sudden  or  prompt  eo   that  such  a  catapulting 
action  is  not  often  seen  in  these  forms* 

a:  refj.e^  tft   tjhe,  aPVffMt  SLL 


resistance  ^o,  Jjhe  step* 

The  relation  of  the  attaching  reflex  to   the  amount  of 
resistance  to  the  step  was  obtained  in  the  following  manner* 
One  of  the  rays  of  an  Agjfcer^na.  was   tied  by  a  long  thread 
to  a  spring  recorder  which  was  calibrated  to  grams  and  set 
to  writhe  on  a  slowly  moving  drum.     Ihen  the  animal  pulled 
against  the  spring,    the  strength  of  the  pull  was  recorded  as 
the  height  of  the  curve  above  the  base  line.     Now  when  the 
animal  had  pulled  the  spring  up  to  various  heights,    the  glass 
plate  on  which  it  was  walking  was  suddenly  slid  forward   - 
In  the  direction  of  locomotion*       This  resulted  in  an  increased 
tension  on  the  starfish  which  was  recorded  on  the  drum  until 
this  tension  became  sufficient  to  cause   the  animal  to  release 
hold  on  the  substrate*     The  curves  got  by  this  method  were 
somewhat  as  follows: 


1-:          the  fctfMT' given  by  the  starfish  as  it  walka  against 
tht  resistant  j>f  the  spring.  s  was  slid 


3SJ* 


-19- 

forward  and  the  curve  2-3  meaouros   the  amount  of  increased  pull  that 
the  starfish  was  able  to  resist  before  releasing   (at  3). 

The  values  for  12  observation  on  Asterim  are  as  follows!: 


Strength  of  pull 
(2  on  fig.) 


2  g 
3 

5 
6 
9 

12 

18 

18       18 

18 

27 

33 


Releases 
at   (3  on  fig.) 

15  g 

15 

27 

21 

24 

36 

45 


3/2 

7.5 

5 

5.5 

3.5 

2.6 

3 


57 
60 
66 
84 


54  aT 


2.5 
2.5 


Disregarding  the  high  values  of  the  first  three  observations 
due  observably  to  the  fact  that  certain  of  the  tube  feet  were  "re- 
fractory", -that  is,   had  not  become  coordinated  in  the  step  reflex  and 
wers  simply  attaching,   -79  find  that  the  strength  of  attachment  of  a 
tube  foot  is  on  the  average  2.7  times  the  amount  of  pulling  the  tubs 
foot  is  doing  at  that  time   (amount  of  resistance  to   the  step).     That  is 
to  say,    the  tube  feat  are  attached  strongly  enough  to  resist  a  pull 
ab-n.t  2.7   times  as  graat  as  that  to  which  they  actually  are  subjecting 
themselves;  a  facto?  of  safety  against  skidding  on  the  smoothest  surface 
of  2,7.     The  valu*  of  friction  in  the  above  experiment  was  tested  with 
the  starfish  inverted  and  found   to  be  negligible   (about  3  g). 

'Whether  the  relation   (quotient  3/2)   between  the  t-/o  variables 
is  constant,   logarithmic  or  of  some  othar  nature  can  be  told  only 
after  much  statistical  compilation  of  data.      In  Ajtarina  it  seams  to 


-•fit* 


-20- 

be  fairly  constant  within   the  limits  studied* 

In  ffyonopodia   the  relationship  is   even  more  constant, 
though  it  has  a  -wholly  diffe^nt  value  as  seen  from  tha  following 
table:  : 

Strength  of  pull  Release  at  3/53 

(2  in  fig.)  (3  in  fig.) 


9 

18 

2 

18 

33 

1.8 

24 

30 

60 

«A 

2.5 

36 

72 

2 

Here  the  average  quotient  is  2.  06.      The  tube  foot  is  2,06  times  at 
strong   to  hold  as  it  is   to  pull. 

The  difference  in  tha  valu«  of  vlie  figure  ia  due  to  spec- 
ific differences  between  the  two   starfish.      It  is  not  in  any  way 
correlated  with  ability  of  the   tube  feet  to  attach  when  not  in  th« 
locomotor  state.     An  attached  stationary  Asterina  is  very  easily  re- 
moved  from  the  substrate  and  only  once  have  I  seen  a  tube  foot  torn 
off  in  the  process.    On   the  other  hand  Pyono  podia  the  attachment 
of  whose  tube  feet  during   the  st*p  reflex  is  much  less  than  that  of 
Aaterina.    would  when  in   the     stationary  clinging  state  hold  with  such 
tenacity  to  the  substrate,    that  it  was  only  with  much  patience  and 
the  loss  of  many  of  the  animals  tuba  feet  that  I  could  pull  it  loose. 
When  the  starfish  was  once  released  from  the  substrate,    if  the  ten- 
dency to  attach  continued,   as  it  often  did,    I  was  confronted  with 
the   equally  difficult  and  much  more  unpleasant   task  of  releasing  the 
animal  from  my  own  hands.      I  have   spent  the   best  part  of  an  hour  dis- 
entangling   the   twenty-two  arms  of  an  eighteen  inch  Pyppnop  o  iia_  from 
myself  and   the  side  of  the  aquarium* 


- 


'ub 


-21- 

g£  the  stop  reflex  (Pulling  ability) 


Hot  only  does  the  ratio  of  strength  of  attachment  to  strength 
Of  pull  #  vary  between  different  species,  but  also   the  pulling  ability 

#       Soheinmetz   (1896)   states  that  a  starfish  (Aetsrias  gluoialis)  is 
able  to  exert  a  pull  of  1360  g  in  opening  a  bivalve,    to  which  pull  the 
bivalve  gave  way,   under  experimental  conditions  in  short  order*     His 
method  of  measuring  the  pull,   however,  was  directed  rather  to  measure 
the  strength  of  the  attaching  reflex  because  he  recorded  the  pull  that 
caused  a  starfish  to  let  loose  its  prey  and  not  the  puU  which  would 
overcome  a  maximal  contraction  of  the  longitudinal  musculature  of  the 
tube  feet*     The  amount  of  pull  exerted  by  a   tube  foot,  under  conditions 
of  locomotion  at  least,   is  aa  we  have  seen  from  one  -half  to  one-third 
of  the  strength  of  attachment  at  that  moment*     Soheinmetz  in  this 
interesting  paper  also  lists  five  ways  in  which  the  starfish  has  been 
supposed  to  open  Oysters;  :  (1)   by  taking  the  mollusc  by  surprise,    (2) 
by  besetting  the  oyster  90  long  that  it  would  be  compelled  by  hunger 
and  want  of  air  to  open.  (3)  by  hypnotizing  the  molluscs,    (4)  by  boring 
through  their  shell,    (5)  by  poisoning  them,   all  of  which  he  shows  are 
fallacious*     Beamur  (1710)  quotes  Aristotle  and  Pliny  as  attributing 
to   the  starfish  a  body  heat,   by  which  it  kills  its  prey,   derived  no 
doubt  by  poetic  analogy  from  the  stare  of  heaven*     He  himself  believed 
tint  the  starfish  pries  open  the  oyster  with  its  oral  spines  and  sucks 
out  the  meat  with  its  laouth* 

considered  alone*     Tor  instance,  a  small  specimen  of  Pisactar  about 

12  cm  in  diameter  was  attached  one  noon  to  the  recording  spring  and 
induced  to  pull  against  it*     During  the  whole  afternoon  the  tension 
varied  between  40  g  and  60  g*     The  drum  was  removed  and  the  animal   left 
tugging  at  the  thread  all  night*     The  next  morning  it  was  pulling  in 
the  same  direction  but  had  advanced  slightly*     The  tension  during  that 
whole  day  varied  from  95  to  190  g*     There  was  much  activity  of  the 
tube  feet  when  the  animal  was  going  forward  or  being  pulled  back  by  the 
spring*     When  the  animal  was  holding  stationary  tube  feet  were  seen  to 
be  arrested  in  the  various  phases  of  the  step  reflex  so  that  only  a 
portion  of  them  were  extended  forward  at  such  an  angle  that  they  could 
pull  the  animal   forward*     Toward  evening  the  pulling  increased  and 
somewhere  between  seven  and  nine  p*m*  reached  a  peak  of 


225  g*   This  came  from  a  sudden  increase  of  pulling  as  shown  by 
the  curve  and  resulted  in  the  arm  breaking  off  where  it  was  tied* 
The  animal  had  thus  pulled  steadily  at  a   tension  of  from  60  to 
225  g  for  a  period  of  over  33  hours*     Another  specimen  18  cm  in 
diameter  pulled  300  g  when  it  was  released  for  fear  of  breaking 
the  apparatus* 

Correlated  with  the  fleet  that  Asterina.  never  attaches  as 
tightly  as  does  Piaster  is  the  faot  that  it  never  pulls  as  hard* 
A  10  oca  Aaterina,    registered  pulls  of  60,   77,    69,  and  46  g*   in 
four  successive  trials*     A  smaller  (8cm)  but  more  active  As te ring 
pulled  90g*     2he  peak  of  the  curve  would  be  reached  after  a 
gradual  ascent  of  about  20  minutes*     de  decline  would  last  from 
one  to   two  hours*     Both  the  decline  in  the  height  of  the  curve 
and  the  fact  that  the  pull  did  not  last  long,    comparatively,  are 
perhaps,   evidences  of  fatigue* 

To  test  the  role  of  the  attaching  reflex  in  this  response,    the 
animal  was  put  on  sand  and  set  to  pulling  in  the  same  way*       the 
best  pull  it  could  record  was  ?i  g*     A  40  g*  (weight  in  water) 
Syracuse  dish  was  laid  on  top  of  the  animal*     This  increased  its 
pulling  ability  to  15  g.     The  adding  of  weight  to  Asterina  or 
Pisaatar  when  pulling  on  a  solid  substrate  made  no  appreciable 
difference  in  theAr  puHling  ability* 

The  case  of  Pyonopaj&ia  #  is  different  as  we  shall  see  later. 


£         Soheinmetz ^1896)  states  that  with  respect  to  food  taking, 
starfish  may  be  divided  into  two   types,   those   that  swallow  their 
food  whole  such  as  Astro  pec  ten    and   those  that  pull  open  the 
bivalves  on  which  they  feed  and  digest  them  by  extruding  their 
stomach  and  applying  it  to   the  soft  parts  of  the  mollusc*    (Asterias) 
Although  fyonopodia  is  grouped  in  the  loroipulate.  with  AsteriaS. 
and  has  tube  feet,    inoontradlstino  tion  to   those  of  Astro  pec  ten. 
capable  of  tight  attachment,    it  swallows  its  footjwnole,  ejecting      •• 
the  (indigested  parts*     Correlated  perhaps  with  the  fact  that  the 
animal  does  not  pull  open  its  bivavle  prey*  as  do  most  of  the 
other  ?orcipulata,    is  the  faot  that  under  other  conditions  as  well, 
the   tube  feet,    though  the;,    can  tightly  attach,   do  not  ordinarily 
do   so  when  pulling,   and  consequently  the  animal   can  not  pull  very 
hard*  


-22- 

i»  different  no  »e  sUali-  see  late*.     The  animal   studied  in  this 
respect  *as  about  50  on  in  diameter,  with,   aooording  to  Verrill*s 
estimate  about  22,000  tube  feet,    each  of  whioh  was  extremely 
aq tire.     In  water  the  animal  weired  only  50  g.  but  in  air  the 
weight  was  estimated  to  be  well  over  1000  g.     Suoh  a  starfish 
when  set  to  pulling  against  the  recording  lever  pulled  54,  45, 
30,60  g*  jin  four  trials  (  on  different  days).      The  time  relations 
were  similar  to  those  of  ftetorinals  pulling  reaction  (less  than 
half  an  hour  of  inoreasing   tension  and  up  to   two  hours  of 
declining  tension), 

The  remarlcable  faot  that  this  large  and  active  starfish  should 
not  pull  marly  as  hard  as  an  8  om  ftstarina.   or  less  than  one  fourth 
as  hard  as  a  12  am  Pj.sa.ster.  wae  thought  perhaps  to  be  due  to 
failure  of  the  attaching  reaction  during  the  step-reflex,   to  keep 
the  same  relationship  with  the  resistance  to  the  step  (pull)   for 
these  higher  values,   whioh  it  has  shown  according  to  the  above 
table  for  lower  levels*     Some  tube  feet  were  seen  to  slip  on 
the  glass  as  they  performed  the  step  reflex*     Other  tube  feet 
were  seen  to  be  in  the*refraotory  state*   that  is  to  be  attached 
tightly  and  to  be  showing  no  sign  of  the  step  reflex.  This  made 
it  impossible  to  get  direct  evidence  as  to  the  status  of  the 
attaching  reflex  in  the  looomotor  tube  feet,  as  the  "refractory" 
tube  feet  caused  the  release  to  be  abnormally  high* 

Besides  direct  observation  of  slipping  tube  feet,   indirect 
evidence  that  the  lacfc  of  pull  was  due  to  failure  of  the 
attaching  reflex  in  the  active  tube  feet,  was  furnished  by  Wti/wcj 
*bala*iittg"   the  animal  with  80  ga  (weight  under  water)  of  Syracuse 
dishes  placed  on  its  dorsal  side.  When  so  weighted  down,   the  value 
of  the  54  g.  pull  was  increased  to  69  g.  and   the  value  of  the 

60  gtt  pull  was  increased  to  75«     The  increased  pulling  ability 
was  undoubtedly  due  to  increased  friction  between  the  tube  feet 


*»• 


-23- 

and  the  glass •   It  also  involved  the  trenching  loose  of  a  number  of 
refraotory  tube  feet. 

On  sand  it  was  found  that  the  animal  could  pull  15  gm 

W'ltll 

(  without  load)  and  tfce  a  load  of  80  gm 

oould  pull  about  '62  gm* 

OUORPINAVK.^f  OF  TH;;    TUB&   g&ffi 

Preliminary  description. 

When  starfish  were  suspended  and   the  tube  feet  at  the  end 
of  one  of  the  rays  brought  in  oontiot  with  some  solid  object,   those 
that  touched  it  first  ~?are  usually  observed  to  attach*     Then  the 
neighboring  tube  feat  orient -3d  and  extended  themselves   in  the  same 
direction  13  the  attached   tube  feet*     If  opportunity  offered  theae 
other  tube  feot  attached  as  did   the  first  tube  feet* 

If  no'*  these  tube  feet  are  stimulatad  sharply  they  retract 
and  the  neighboring  tube  feet  also  retract   (Roman*  and  >iwert  1881, 
Prayer  1836,   etc*,}*     The  wave  of  retraction  passes  down  the  stimula- 
ted arm,   and  out  the  other  arms  along  the   line  of  the  ambulacra! 
nervous  system.     This  is  in  accordance  with  the  older  observers,    es- 
pecially Preyer   (1386)*     They  also  stowed  that  if  the  nervous  syatea 
was  cut  <*t  some  point  the  above  coordination  would  extend  as  far  a» 

the  cut  and  no   farther* 

r 
Further  than  the  fact  that  it  rests  in  the  ambulaoial 

nervous  system,    the  mechanism  of  this  coordination  is  very  obscure* 
Physiologically,    it  is  a  fact  attested   so  far  as  I  am  aware  by  all 
of  the  workers  on  this  phase  of  echinodezm  physiology*     one  tube 
foot  seems  to   "imitate"  in  its  activity   th«  behavior  of  its  neigh- 
bora*     In  the  following  analysis  of  coordination  in  the  tube  feet 
we  shall  inquire  into  its 


•24* 

characteristics  la  the  rigid   starfish,   and  compare  it    vith 
the  ooordination  manifested  by  the  gills*     '**  wtti    ilso  inquire 
into  coordination  in  tube  feet  of  active  but  non-oriented   starfish, 
the  building  up  of  this  ooordination  into   the  Unified  impulse, 
the  behavior  of  tha  starfish  under  the  influence  of  the  unified 
impulse  and  the  breaking  do-am  of  this  unified  impulse  under 
various  normal  and  abnormal  conditions, 

Coordination  i&  the  tube*feet  g£  the  rigid  '.atjarfish, 
When  rigid   speoimene  of  Pisaster  were  suspended  or  inverted 
the  tube  feet,   after   their  temporary  retraction  from  the  stimula* 
tion  of  loosening,  were   found  to  extend  more  or  less  at  right 
angles  to  the  body  of  the  ray.     There  were  subsequent  movements 
of  the  ray  *hioh  vill  be  considered  later*     Some  of  the  tube  feet 
were  then  stimulated  to  retract*     There  was  a  wave  of  retraction 
passing  along  the  lines  of  the  tube  feet*     This  lessened  in 

&  d'ld 

intensity  as  it  proceeded  from  its  source,  so  that  it  «*y  no 
reach  the  farthest  tube  feet.  Later  the  tube  feet  W»M  again  extend 
the  wave  of  extension  pawling  back  in  the  reverse  order  so  that 
the  tube  feet  stimulated  to  retraot  and  those  nearest  them  will 
be  the  last  to  re  extend* 

To  account  for  this  ooordination  in  retraction  and  extension 
it  is  not  necessary  to  hypothesise  very  complex  conditions  in  the 
nervous  system  at  the  base  of  the  pedicels* 


^'.uenftt  (1888)  Ludwig  and  Hainan  (1899);tfeyer  (1916)  eto.,X  the 
ambulaoral  nervous  system  seems  to  be  merely  a  condensation 
of  the  nerve  net  that  extends  over  the  outside  of  the  myoderral 
•heath*       So  far  aa  I  am  aware   there  is  no  morphological  evidence 
of  synapses  in  the  nervous  system  of  starfiahos,    though  of  course 
the  evidence  on   this  question  is  far  from  complete*  A  simple, 
nerve  net  will  account  for  the  above  behavior* 


• 


-25- 

Jt  has  been  Been  that  an  isolated  tube   foot  will  not 
contract  or  extend  quite  normally.     Certain   conditions   then  may 
be  said   to   exist  in  the  nerve  net  at  the  base  of  the  stimulated 
tube  foot,   which  affect  the  muscles  of  the  pedicel  and  ampulla  and 
cause   the  normal  withdrawal    (or  extension)   of  the   tube  foot.     Now 
in  accord  with  the  well  known  laws  of  transmission  of  excitation 
in  a  nerve  net  (Parker  191^    these  conditions  may  spread  in  any 
direction   (within   the  ambulacjal  nvrvous  system)  and   cause   the 
retraction  or  extension  of  other  tube  feet.     We   shall   see, 
elsewhere   that  no   such  simple   condition  will  account  for  the 
physiological  orientation  of  the   tube  feet  and   their  coordination 
in  locomotion. 

Coordination  ig.  gills. 

The  physiology  of  movement  in  the  gills  is  quite   similar  to 
that  of  the  tube  feet  in  the  rigid   starfish.     Although  there  is 

lateral  movement  in  each  there   is  no  orientation  of  these  lateral 

(fa  4-W^u*- 
movements  in  any  particular  direction  in  the  gills.     A-  stimulus 

will   cause   the  contraction  of  one  group  of  the  (dorsal)  gills, 
will  be  communicated   to  others  near  these  and  cause 


their  retraction  (Jennings  1907).     In  this  region   the  nerve 
net  is  quite  diffuse,    so   that  the   spread  of  the  contraction  may 

be  in  any  direction.     The  wave  of  r«  -extension  usually  takes  Adm^cn 

-t* 
opposite  atii-tfutiun   rrum^that  of  contraction.      It  is  centripetal 

rather  than  centrifugal.       If  the  wave  of  retraction  is  sufficiently 
strong  it  may  be  communicated   to  the   tube  feet  and  involve  their 
retraction  as  well.     The   retraction  of  the  tube   feet  does  not 
involve   the  retraction  of  the   (ambulaoral)  gills   (De  Moor  &  Chapeaux 
1691)  an  evidence  of  polarity  in  the  nerve  net  which  suggests 
something  in  the  nature  of  a  synapse.   That  part  of  the  nerve  net 
whicfe  extends  up   the  sides  of  the  long  ambulacfal  gills  in 
Pisaster     also   shows  evidences  of  polar^ation   similar/  to    the 


'«'  4,ts.S.r 

-      182  SEX  11 


-26- 

polarity  of  sea  anemone  tentacle   (Psrliser  191$)   in  that  when 
stimulated  at  the  base  or  middle,    th*  musculature,    especially 
the   circular  musculature,    below  (proximal   to)   the  locus  of 
stimulation  contract^     while   that  above   (distal)  dt>e$  not  contract. 
If  stimulated  at   the  tip  the  whole   tentacle  contracts,    the 
circular  musculature  responding  to  a  lesser  stimulation  than  the 
longitudinal.      If  out  off  at   the  base  with  scissors,    the 
edges  of  both  the  stump  and  the  ablated  piece  adhere  together 
along  the  line  of  the  out  by  means,    seemingly,   of  a  sticky 
substance  on  or  near  the  cut  edges,    so   that  the  wound  does  not 
open  an  ^pJJ&rKture   to   the  exterior.     The  stumps  of  course 
shrivel  down  in  strong  contraction.      They  are  found,    three  days 
later  a  little   short  but  with  the  end  healed     over  normally. 
The  excised  gills  show  no   sign  of  contraction,   and   the  cut  end 
being  sealed  over  as  describedabove,    the  gill  remains  distended 
by  its  enclosed  watef  like  a  miniature   "sausage  balloon"  with 
a   trun^a^ed  end.   The  contraction  of  the  gill  musculature  is  not 
sufficient  to   collapse  the  gill  against   the  resistance  of  the 
closed  end.      If  this  end  be   teased  open  gently  and   then  the  tip 
be  stimulated  collapse  ensues  immediately* 

Ciliary  currents  in  frills. 

«J 
One  of   the  gills,  when  thus  removed  was  seen  to   en&ose 

several   clumps  of  amoebocytes  or  wandering  cells.      These  made  it 
convenient  to  see   the  ciliary  respiratory  current  which  continued 
uninterruptedly  after  the  gill  had  been  removed.   The  amoebocytes 
moved  up  one  side  to   the   tip  of  the  excised  gill  and  down  the 
other  side  to   the  base*     It  took  three  or  four  seconds  to  complete 
the  circuit. 

Coordination   that  involves  some  orientation  of,  the  tube  feet. 

Having  studied   the  coordination  of  the  non-looomotor  tube 

if 
feet  and  compared   #*a-fcwith  coordination  of  the  gills  we   shall 


already  seen,    they  will  attach.      This  ia  usually  followed  by 


-27- 

now  take  up  coordination  in   the  behavior  of   the  tube  feet  during 
their  transition   stages  between   the  looomotor  and  the  non- 
looomotor  state* 

If  a  rigid  starfish  be  suspended  and   some  of  the  extended 
tube  feet  be  broughct  in  contact  with  a   solid  object,   as  we  have 

increased  activity  of  the  neighboring  tube  feet  and  if  the 

v 

starfish  is  not  too   rigid,    by  their  active  bending  &  *fcx±x  We® 

» 

toward  the    stimulated    c»re<x     ..      It  is   in  this  phase  of  their 
behavior,    that  the  beginning  of  the  step  reflex  can  be 
elicited  toy   proper  stimulation* 

Coori  j.natip^    tp   passive  movements  of   tub&  feet* 
If  on  such  a   starfish  a  long  tube  foot  be  brought  in 
contact  with  a  small  object,    such  afe  a  pencil  point  the  disc  will 
attach.      If  np'?i,    the  pencil  point  be  moved,    with  the   tube  foot 

still  adhere'ing  so    that  the  direction  in  which  the  tube  foot  iS 

r 
now  pulled  out  is  different   from  that  in  which  it  originally 

extended  itself,    other  tube   feet  will    thencoordinate   themselves, 
not  in   the  direction  of  the  original  extension  of  the  stimulated 
tube  foot  but  rather  in  the  direction  to  which  it  had  been  passively 
moved*      This  tendency  to   coordinate  thus,   while  very  marked  in 
some  animals,    is  of  course  apt  not  to   show  itself  in  starfish  that  ar 
are  very  inactive  or  very  rigid,   and  is  apt  also  not  to 


at  all,    if  there  is  a  strongly  laarked  coordinated  impulse  in 
some  other  direction.         Out  of   thirty  trials  on  starfish  in 
various  physiological   states   there  was  well  marked  and  active 
coordination  to  passive  movement  in  fifteen. 

This   coordination  could  also  be  brought  about  when  the  tube 
f»*t  was   twisted  by  turning  the  pencil  a  few  times  ia  the  hand 
before  pulling  the  tube  foot  over  in  its  new  direction.     I  could 


•• 


-28- 


observed^  no  dif farenoe  in  the  -accuracy  or  promptness  of  the 
coordination,     I  have  even  untwisted  tho  tube  foot  again,    in  its 
new  position,   without  either  disturbing  the  attachment  of  the  tube 
foot  or  the  coordination  of  its  felloes*     Heedless  to   say  these  manip- 
ulations had   to  be  done  with  extreme  care   to  avoid  stimulations  wiiioh 
might  cause  retraction* 

Coordination  £f  the   tube  feet  jjnt  the  active  starfish. 

thus  far  wa  have  baen  discussing  coordination  in  the  tube 
feat  of  rigid  non-looorootor  animals*     But  when  a  very  large  number 
of  tube   feet  are  seen   in  tha   suspended  specimen,    pointing  in  one 

a 

direction  in  ^coordinated  manner,    one  is  apt  to  be  dealing  -vith  a  star* 
fish  in   the  active  rather  than   in  the  rigid  state* 

If  we  suspend  a  starfish  that  is  active,   but  not  definitely 
oriented  and  locomoting  in  any  one  direction,   we  find  that  the  tube 
feet  at   the  tips  and  for  a   centime  tar  or  no  re  toward   the  disk  are 
oriented  and  actively  feeling  out  toward  the  Up*     Proper  stimulation 
of  the  tube  feet  at  the  ends  of  these  rays  will  elicit  the  step  re* 
flex  in   the  direction  of  the  tip  of  the  ray*     This  would  indicate  that 
each  ray  has  a  tendency  to  migrate  in  the  direction  it  points* 

4 

Tand.e.noy.  oj£  each  ray  to.  raipr-atje  ,  to  ward  jLJ^  .LkJL* 
That  each  ray  does  tend  to  migrate  away   from  the  disk  was 
demonstrated  by  attaohing  five  glass   tubes  or  shell  vials,   large  enough 
to  acooaodato  the  ray,    to  five  floats  and  presenting  these  simultaneous- 
ly to  the  tips  of  each  of  the  five  rays,   in  such  a  way  that  they  could 

each  walk  »nto  one  of  the  glass  tubes  and  in  so  doing  pull  it  back  over 
the  ray*     When  the  rays  got  to  the  end  of  the  tubes  they  were  seen  either 
to  keep  on  in  the  same  direction  or  reverse  and  back  out,   or  part  way 
out*      It  was  raally  quite   amusing  to   watch  this   suspended  animal  indus- 
triously 


-29- 

<  >' 

trying  to  walk  in  five  different  directions  at  once. 

Auto  tony 

Another  indication  of  this  tendency  is  the  faot  that  in 
stale  water  or  under  the  influance  of  ohbroform  (Moore  1916) 
a  starfish  is  extremely  susceptible  to  autoton^  Pisaster 

seems  much  more   susceptible   to    this  reaction  if  the  nervous 
system  has  been  injured  in  some  part.     As  I  have  observed  it,    the 
reaction  consists  in  an  exaggerated   tendency  in   the  tips  of  the 
several  rays   to  migrate  in  their  own  direction  and  a  failure 
of   this  tendency  to  effect  an  orientation  rf  the   tube  feet  of  the 
rest  of  the  animal  in   the  way  that  will  be  seen  below  to  be 
usual   in  the  normal   starfish*    This  is   due  to  a  pathological 
sluggishness  in  the  action  of  the  central  part  of  the  ambulacral 
nervous  system,    as  seen   from  the  fact  that  the   tube  feet  in   that 
region  are  comparatively  inactive.   The  raye  of  a  Piaaster  atwzatf 
U'-vvd-t/w^tri^v^^      ' -f  autotomy  present  an  elongated  appearance. 
The   tube   feet  at  the   tip  pull  actively,    each  in   the  direction 
of  its  own  ray,    so   that  after  stretching  somewhat  the  ray  gives 
way,   usually  at  or  near   the  base. 

FORMATION  OF   THS  UNIFIiiH)   IMPULSE 

/  -  , 

o< 

From   such  a  picture  as   the  above   it  may  seem  as A far  call    to 
the  unified  behavior  of  the  actively  walking  starfish.     In  the 
latter  each  tube   foot  is  put  out  in  a   single  definite  direction  and 
locomotion  proceeds  in  a  beautifully  unified  and  coordinated 
manner.   The  difference  is  ttm  Just  this,    that  in  the  unified 
locomotor  starfish,   one,    or  more  often   two  adjacent  rays  become 
for  some   reason  more  active   than   the  others  and  the  coordinated 
state  which  is  present  at  their  tips   spteads  maintaining  its 
own  direction  and  gaining  impetue,   over  the  other  rays. 

It  u>\\^ ..  be  our  purpose  now  to  inquire  into    the  factors  which 
give  precedence   to   the  activity  of  some  ray  or  rays  in  the 


-30- 
formation  of  the   "unified  impulse". 

The  responses  of  a   starfish  to  stimuli,    in  so   far  as   they 
involve  locomotion,  may  be  divided  into  two  categories,   positive 
responses,    in  which  the  resulting  locomotion  is   toward   the 
stimulus,    and  negative  responses,    in  which  the  direction  of 
locomotion  is  aw->y  from  the  stimulus.      Gentle  contact  at   the 
ti£  of  the  ray  will  usually  elicit  a  positive  response  while  a 
negative  response  usually  results   from  severe  prodding  or  pinching. 

General  statement  of  the  mechanism  oJT  the  positive  response. 

The  mechanism  of  the  positive  responses,    is  as  I  see  it 
as  follows?  A  gentle  contact  stimulation  of  the  tube  feet  at  the 
end  of  a  ray  causes   these  tube   feet   to  extend  in  the  direction 
of  the   stimulus  as  we  have  already  seen,     other  tube  feet  behind 
this   coordinate  in  this  action,    and  receiving  the  contact 

..  i  i  '         i  "Hi  >•»  ** 

stimulation  of  the  substrate  execute  the  step  reflex*     The 
impulse  to   coordinate  with  the  active   tube  feet  at  the   tip  of  the 
stimulated  ray  this  spreads  to   the  rest  of  the  starfish,    involving 
after  a   time  every   tube  foot  in  the  body  in  coordinated  locomotion. 

General  description  of  the  negative  response. 

The  negative  response  is  brought  ab*at  on  exactly  the 
same  principle.      The  prodding  or  pinching  of  a  certain  ray 
results  in  the  retraction  or  inactivation  of  the  tube  feet  in 
that  region  and  aa>  •&p^3a@W)s&8&  vo  the   spread  of  this  impulse, 
to   certain  of  the  other  tube  feet.   The  extent  of  the  spread  is 
of  course  determined  by  the   strength  of  the   stimulus* 

Assuming  first  that  the  stimulation  is   severe  enough  to 
cause  all   the  tube  feet  to  retract  or  become  inactive,  H 

the  first  tube  feet  to   resume   their  normal   function  are 


those  farthest  away  from  the   source  of  stimulation.      In   this 
experiment  the  tube  feet  farthest  away  are  those  of  the  opposite 
ray  tips.      These   tube  feet  are  ori'rlejted  in  the  direction  of  their 


-31- 

which  is  in  fact  away  from  the  source  of  stimulation*        In  so 
doing  they  come   in   contact  with  the  substrate  and  execute   the 
step  reflex*   From  this  point  on  ;  the  coordination  completes 
itself  in   the  same  manner  as  outlined  for  the  positive  response* 

In  case   the   stimulation  it  not  sufficient  to   cause   the 
retraction  or  inaotivation  of  all   the  tube  feet,    it  will  spread 


the  tube  feet,    to  a   certain  extent  so   that  the   farthest  tube 
feet  are   the  most  active  and   therefore  will  dominate  in  the 
coordination* 

Detailed  description  ojF  positive  aftd  negative  response  in 
Hrcnopodia. 

FHono  podia  on  account  of  its  large  size  and  great  activity 
is  very  favorable   for  a  study  of  the  mechanism  of  coordination 
in  positiw  and  negativ*  -"-a-nonaes.     The  active  but  not  oriented 


,qu 


a  the   tube  feet  at  the 

tip  oi  Sited  in   the  direction  of  the  ray,   and 


r  upon  proper  stimulation.     Now 

A  I  A 


convinced  me  that  a  positive  stimulation 

f  coordinated  activity  in  the 

C 

ordinated  activity  in  the  way 


. 


-32- 

dlagraaed  above^     Inthis  way  <pand  d  will  be  coordinated  before 
b   though  b  and  the  neighboring  raya  «ay  be  ;oore  active  in  their 
coordination   than  o  and  d  because   they   receive   stimulation 
throu^i    the   rin  :   fro;.;  both  directions   simultaneously. 

Now  with  the  negative  #  response,    conditions  are  different 

#  The  negative  response  has  been  described  by  Loeb   (1900) 
in  terms  cf  observations  by  Norman   (1900)  as  a  result  of  the 
retraction  of  tube   feet  on   the  harshly  stimulated  ray  and  a 
consequent  determination  of  the  direction  of  the  negative 
responses  by  a  "parallellogrim  of  forces"  exerted  by  the  other 
rays,    each,  hypothetioally,  as  I  take   it,  continuing,   during  the 
negative   rotation    to  pull   in  its  ewn  direction.      It  is  -«eil  icnown 
from  the  -/ork  of   l-tomanos,    Preyer,   Jannings,   Mangold,    Cole  and 
others   tjiat  all   normal  locomotion  is  brought  about  by   the  cooper- 
ation of  all   of  the   tube   feet  stepping  in  one  direction  and  not 
«£  the  divergent  pulls  of   the   various   ra   s,    which  as  w«  have  seen 
results  in  autotomy. 

in  certain  respects.     Assuming    that  the  harsh  stimulus  is  given 


at  b.      The  p*tk  olLJEtttraaUoa  «JU1  w»  a*  above    (        but   the  Way 
the  coordination  impulse   spreads  is  tmtz  identical  with  that 

|X 

diagrammed   in   fig.    2   so   that  o_  and  d.  become  oocrdinated  before 
b,   which  is  the  location  of  the  stimulation. 

Appearances   seem  to   indicate   that  just  after   the   retraction 
following  such,  a  negative   stimulation,    the  tube   feet  on  the 
far   side  of   the  animal   show  a  definite  increase   in   activity. 


J.SO 


Whether  this  increase  is  only  relative  or  to  what  extent  it  is       absolute 
I  am  unable   to   say* 

Eunotion  o^  the  qtej  reflate  jji   the  spread  gf,  coordination* 
The  function  of  the  step  reflex  in  the  spread  of  coordination 
ia  probably  very  Jj.iocrt«it»     The  pinching  of  one  ray  of  an  Aet^rina  will 
cause  prompt  negative  locomotion  with  all  the  tube  feet  coordinating* 
If,  however,    the  starfish  is  inverted   there  ia  little  likelihood  that 
the  impulse    rLll  include  coordination  of  all    the  tube  feat,   even  after 
the  severest  pinching*     The  only  difference  between  the  animal*  in  these 
two  positions  io  that    the  tube  feet  of  the  inverted  starfish  are  not 
executing  the  step  reflex  because  there  is  no  contact  stimulation  to   set 
it  off*      I  am  inclined   to  think  therefore  that  a   state  of  orientation 
spreads  much  raore  rapidly  <*here  the  tube  feet  are  executing  the  step 
reflex  than  -ziiere  thoy  are  not*  Thtj|_l»_a  Iso   true  of  Pisa  a  tor  to  a  lesser/ 
extent,   but  in  cane1  of  Pycnopodia  it  seems  to  make  but  little  difference 
whether  the  tube  feat  are  in  contact  with  the  substrate  or  not*     The 
coordinated  impulse  is  easily  initiated  and  very  active  in  this  animal* 

the  common  or  usual  manner  in  which  the  coordinated  impulse 
is  formed  in  starfish  is,   X  think  in  general  accord  with  the  above  out* 

~VX+:VV    •>->   \/~ 

line*     There  *ra  very  many  species  of  starfish,   each  differing  more  or 
less   in  its  structures  and  functions  from  the  other  so  that  ideas  de- 
rived from  the  study  of  five  or  six  epeoies  might  not  fit  the  behavior 
of  all  of  the  thousands   known  to  science* 

1  have  sean  PycnoBo^A*  ?jfl-j9aatgir'   Aftt^rinA  gjid,  ^japt^ria.s, 
regularly  orient  to**ard  or  away  from  contact  and  charaleal   stimulations 
(mussdl  juice  or  dilute  acid)   in  the  manner  outlined  above,  and 
a  bsam  of  direct  sunlight  waa  thrown,  on  the  eya-spot  of 
the  response  was  analogous  to  that  to  contact. 

Orientation  .*&  £  result  gf.  stimulating  thji  d 
ox  a.  general   stf^m^l^ti^n  of.  ajjj^  thja   tube 


-34- 

The  responses  of  the  starfish  to  light  #  have  been  divided 
by  Plessner  (1913)  into  two  categories  those  (both  positive  and  nega- 
tive) in  which  the  eye  spot  aots  as  the  receptor  and  those  in  which 
the  receptors  are  distributed  over  the  surface  and  connected  with  der- 
mal nerve  net.  Inasmuch  as  it  is  the  whole  surface  which  possesses 
these  receptors  and  not  merely  that  at  the  tip  of  the  ray,  it  would  b« 
well  here  to  look  into  the  qualities  of  the  orientation  of  the  tube 
feet  and  their  coordination  that  can  be  brought  about  through  stim- 
ulating  the  body  wall. 

In  starfish  which  are  suspended  and  the  body  wall  at  one 
side  of  a  ray  stimulated  by  gentle  contact  I  have  observed  that  th« 
tube  feet  in  that  region  show  a  tendency  to  orient  themselves  in  the 
direction  of  the  stimulus.  Upon  increasing  the  strength  of  the  stim- 
ulation of  the  body  wall,  the  tube  feet  near  the  stimulated  area  under- 
go retraction  which  spreads  in  proportion  to  the  strngth  of  the  stim- 
ulus.   I  have  s^en  no  orientation  of  the  tube  feet  directly  away  from 
the  stimulus  even  though  the  stimulus  be  graded  in  intensity  as  care- 
fully as  possible.  The  response  is  either  orientation  toward  th« 
stimulus  or  retraction. 

In  the  above  experiment  we  have  an  explanation  of  a  positive 
response  to  a  dermal  stimulation*  A  negative  response  can  be  regarded 
on  the  above  hypothesis  as  a  positive  reaction  toward  the  unstimulatad 
side,  if  it  should  indeed  prove  to  be  a  fact  as  indicated  above  that  a 
direct  response  to  dermal  stimulation  is  only  positive  in  its  sense. 
Thus  we  may  suppose  that  the  tube  feet  are  oriented  toward  the  side 
which  receives  optimal  illumination,  rather  than  that  they  are  oriented 

#   The  older  observers  on  the  responses  of  starfish  to  light  have 
divided  themselves  into  two  schools*  One  of  these  schools  regarded. the 
eye  spot  as  a  light  receptor  and  in  it  may  be  listed  Romanes  and  Sw$rt 
(1181),  Oraber  (1885),  Preyer  (1886),  Bonn  (1908).   The  rnorphologists 
favored  this  view  also.  The  second  school  regarded  the  light  receptors 


- 


,  • 


I  ,  i 


••36* 

as  in  the  derails  or  tube  feet.     Mangold    (1908).    Cowles    (1911a),   Mast 
(1911),   and  others  adhered  to   this  view  more  or  loss  explicitly.     The 
ingenious  experiments  of  Plesner   (1913)  hare  made  it  seem  quite  proba- 
ble  that  the  starfish  responds  to  direct  illumination  of  the  dermis  and 
that  the  eye  spot  receiver  stimulation  from  distant  areas  of  Hoht  or 
shadow  to  which   tUa  starfish  res  onds  also*      This  results  in  a  very 
puzzling  aggregate  of  reactions  as  the  controversy  attests* 

away  from  the  side  that  is  in  a  state  of  sub  or  super  optimal  illumina- 
tion, 

Significance  of  the  negative  brehavipr  ojf  the,  jj-golatod  rayu, 

The  negative  behavior  of  the  isolated  ray,    is,   as  has  been 

long  inown,  much  less  definite  than  that  of  the  whole  animal*     Romanes 

and  Kwart   (  1831,   p.   1356)   state  that  "Single  rays  detached  from  the 

organism  crawl"  sometimes  a^ay  from  injuries,   but  they  do  not  invar- 

A 

iably  or  ovan  generally  seek  to  escape  from  the  latter  as  is  so  certain 
to  be   the  ciae  with  the  entire  animals"*     In  confirming  this  it  was 
found  that  a  migrating  ray  which  had  been  isolated,  wffttld  give  Very 
irregular  responses  to  stimuli  which  would  cause  negative  behavior  in  a 
normal  animal*     A  negative  response   to  pinching  or  prodding  is  the  ex- 
ception, -rather  than   the  rule  in  the  behavior  of  isolated  rays*     This  la 
to  be  exp30t3d  in  the  light  of  what  h*s  been  said  about  the  nature  of 
the  negative  response  because  the  "rays  opposite  the  stimulus"  are  not 
there   to  unfailingly  initiate/  a  migration  away  from  the  stimulus* 

—  _  .  ^ 

BSHAVIQR  pv  TjB   STARFISH  1H5W  UKDSH   Tflft  ISFLUI2TCS  0? 

IMPULSS 


Having  studied  the  factors  which  govern  the  formation  of  the 
"unified"  impulse  we  shall  now  turn  our  attention  to  the  behavior  of  an 
animal  under  the  influence  of  this  physiological  state,    first  taking 
up  the  factors  which  cause  a  change  in  the  "physiological  anterior" 
and  factors  which  cause  a  change  in  the  direction  of  locomotion  of  the 
starfish  by  a  rotation  of  the  body  as  a  whole  without  changing  the 
•anterior  rays. 

the  factors  which  cause  a  change  in  the  physiological  anterior 


•t»  mo 


'£  MM 

i*:. 


fit 


EYO^Dfft 


#* 

»T 


-36- 

are  essentially  the  same  as  those  which  determine  the  anterior 
as   the  impulse  is  being  foriae*  and  operate   through  the 
same  mechanism,      .vith  respect   to   the   sense  of  the  reaction  which  thy 
elicit  thay  can  therefore  be  grouped  into    (1)   the  positive  and 
$2)    the  negative.     With  respect  to    the  receptors  on  whicn  they 
•perate  they  can  be  grouped   into    (1)    those  acting  «a  the  dermis  and 
directly  on  the  tube  feet  and(*)those  acting  on  the   terminal   tube 
feet  of   the  rays    (or  eye  spot  which  is  a  modified   tube  foot). 
Such  Common  factors  in  the  environment  of  the  starfish  Contact 
chemical   stimulation  and  £g±±  light  have  been  seen   to  affect   the 
Unified  impulse   in  the  uncoordinated  starfish  in  one  or  more 
of  the  above  mentioned  ways  and  it  will  be   seen  from  the  following 

that  they  affect   the  coordinated  impulse  once  it  is   started  in 

' 
the  same   sense  and  in  the  same  way* 

Po si tive  reaction  tor   contact 

tOhen. 

$£  one  of  the  ray  tips  of  »  starfish  migrating  actively 
under  the  influence  of  the  "unified  impulse"  bruslWagainst  the 
side  of  the  aquarium  the  tube  feet  at  the  end  of  this  ray  luve 
been   seen    *p  stretch  out  actively, those  behind   them  coordinated  and 
soon   the  direction  cf  locomotion  changed   and  the  animal  was 
walking  up  the  side  of  the  aquarium 

Iterative  reaction  to_  con  tact 

On  pinching  one  of  the  rays  of  such  a,locomotor  starfish, 
serial  retraction  or  inaotivation  of  the   tube  feet  will  ensue 
spreading  more  or  less  among  the  tube  feet,    but  last  and  least 
effectively  to  the  tube  feet  of  the  opposite  side  of  the  starfish. 
The  lalle-r     y-«^«-»wie     <a«4\ViTy  first  and  orient  mor« 

nearly  in  the  direction  of  the  ray  on  which  they  are  borne  i.e. 
away  from  the  source  of  stimulation.      The   tube  feet  behind  these 
coordinate  themselves  with  them  in  the  same  direction  so   that  the 
coordinated  impulse   (to   ;#  away  from  the  stimulus   )   spreads 


t   M'      » 


-37- 

baok  about  as  quickly  as   the  tube  feet  become  active  again. 

Chemioal  stimuli  #  and  light  (acting  on  the  eye  spot)  have 

also  been  seen  to  affect  the  loooraotor  starfish  in  a  way  wholly  anal- 

#  Romanes  1883  states   that  all  of   the  under  side  of  the  star- 
fish  is  sensitive   to  odor   (chemical   stimulation)  while  Pro.uho      (1890) 
localized   these  receptors  in   the    terminal   tube   feet  of  the  rays. 

ogous   to   the  above. 

Physiological  a^s  distinguished  from  physical  orientation. 

I  have  described   above   such  changes  in   the  direction  of  a 
looomotor  starfish  as  involve  also  changes  in  the  leading  ray,-  that 
is   the  animal  may  be  going   in   the  direction  of  a    certain  ray  before 
the  change  and  ia  the  direction  of  the  opposite  rays  after  change.      It 
is  a  matter  of  common  observation,   however,    that  crawling  starfish 
sometimes  change   their  orientation  by  a  rotation  of  the  body  as  a 
whole  without  changing  the  anterior  ray.     This  is  a  less  common  method 
of  changing  direction,  and  is  said   (Bohn  1908)   to-be  more  frequent 
anng  large  and  stiff  specimens   than  among  small  active  ones. 

Orientation  of  this  kind  may  be  called  "physical  orienta- 
tion"  to  distinguish  it  from  "physiological  orientation"  which  involves 
a  change  of  the  leading  ray. 

Physical  orientation  may  involve   three  f  ictore,   any  one  of 
which  may  be  more  or  less  completely  predominant.     These  are::  (1) 
Direct  orientation  of  the  leading  ray  or  rays  to  one  side:    (2)  ao» 
celeration  of  the   tube  feet  of  one  side  of  the  starfish  and  a  conse- 
quent swinging  of   the  anterior  rays   in  the  opposite  direction:    (3) 
the  retardation  of  the  tube  feet  on  one  side  of  the  starfish  and  the 
consequent  swinging  of   the  anterior  rays  toward   the  same   side. 


$r 


38 


Direct  orientation  of  the  leading  ray  or  rays   to  one  side 
is  dependent  upon  a  unilateral   stimulation  of  either  the  dermis, 
the  eye  spot  or   the   tube   feet  of  these  rays  and  a  consequent 
orientation  of  these  rays  toward   (or  away  from?)    the  stimulus. 
If  the   stimulus  acts  also  on   the  rays   that  are  situated  on  the 

side  of   the  starfish  from  which  the  stimulus  comes,    the  anterior 

^  X 
is  apt  to  be  shifted    (Pless*er  1913)    to   these  arms  b^t  if  it 

acts  only  on  the   side  of  the  anterior  arms  it  is  more  likely  to   causa 
a  rotation  of  the  animal  as  a  whole.     This  is  dependent  upon 
the  angle  of  the  stimulus   to   the  direction  of  the  starfish  and 
various  other  factors  that  have  been  analyzed  by  Bohn   (1903). 
The  relative  acceleration  and  retardation  of  the  lateral 
arms  is  of  course  a  necessary  result  of  the  above  described 
lateral  movements  of  the  anterior  rays.     As  a  result  of 
stimulation  the  same  factors  which  we  have  discussed  above  act- 
ing in  a  positive  direction  on  the  tube  feet,    dermis  or  eye 
•pot  would   cause  acceleration  and  in  a  negative  direction  would 
cause  retardation,   provided  the  stimulus  did  not  reach  the 
more  sensitive   (to  a  direct  stimulation)   tips  of  the  anterior 
or  posterior  rays.     A  mechanical  obstacle  to   the  progress  of  the 
rays  on  one  side  of  the  animal  will  result  in  a  change  in 
orientation   that  may  or  may  not  involve  a  change  in  the  physio- 
logical anterior.        This,  however,   will  be  taken  up  in  connection 
with  the"d«viation  reaction"     and  the  breaking  up  of  the 
functional  unity  of  the  coordinated  impulse. 

GJiNflRAk  CONSIDERATION  0£  COORDINATION 

t 

The  categories  into  which  we  have  analyzed  the  reactions 
of   the  locomotor   starfish  are  not  the  separate  and  distinct 
unities        that  they  appear  above.     All   of  the  factors  that  we 
have  recognized  are  usually  at  work  at  one  and   the  same  time* 


•39- 

They  are  nicely  balanced  against  each  other  and  any   stimulus  which 
upsets  the  balance  by  adding  to   the  strength  of  one  factor  or  taking 
from  the  strength  of  another  factor  results  in  a  more  or  less  radi- 
cal change  in  the  behavior  of  tne  animal.     It  is  often  difficult, 
moreover,    to  discern  the  cause  of  a  change   in  behavior,    eo  delicate 
is  the  balance  between   the  different  factors,    and  so  impossible  is 
it  to  keep  track  of   the  changes  of  fatigue,  hunger,    etc*,    that  play 
an  important  part  in  the  relative  irritability  of  the  animal  as  a 
whole,  and  of  its  different  parts  from  time  to   ti;ae.     An  analysis 
of  the  behavior  of  starfishes,   based  upon  observations  and   experi- 
ments on  only  four  or  five  species,    can  not  pretend  to  completeness 
or  to  a  generality  covering  the  whole  group  of  Aateroidea*      (See 
kangold  1908  on   the  self  burying  reaction  of  Astropefltfpl* 
Theories  ojf   the  moohaniap  gjf  coordination.* 
It  is  probably  true  that  all  starfish  locomotion  involve! 
in  some  of  its  phases  at  least  a  "unified  impulse"  among  the  tube 
feat  in  various  p-arts  of  the  body* 

The  mechanism  of  such  coordination  is  of  course  very  com* 
p  lex.  As  cording  to  Von  Uexkull,     vn  the  sea  urchin  it  involves  the 
functioning  of  many  nerve  nets,   connecting  and  supplying  with  simi- 
lar "quantities"  of  "tonus"  homologous  parts  of  the  various  coordi- 
nating organs   (tube  feet,   spines  etc.,).       Pending  adequate  histolog- 
ical  investigations  it  would  be  well   to  state  as  an  hypothesis  that 
since  homologous  parts  of  coordinated  tube  feet  act  in  almost  ex- 
actly the  same  manner  they  are  probably  connected  by  nervous  paths 
of  lower  threshold  than  are  non  homolgous  parts*     'Hie  value  of  such 
speculation,  however,    is  dubious,   and  it  is  better  to  keep  within   thi 
data  of  physiology  in  evaluating  the  coordinated  impulse,   since  the 
morphological  data  is  wanting* 


-40  • 

Orientation  of  re  t  rao  ted  tube  feet  and  the  independence 
mechanisms  of  orientation  and  that  o£  withdrawal  ojr  stepping* 

It  has  been  shown  (dole  1913}    that  the  coordinated  im- 
pulse may  retain  its  orientation  even  after  the  starfish  is  removed 
from  water  and  held  inverted  for  two  minutes*     This  procedure  causes 
the  retraction  of  the  tube  feet  (in  Pisaster)  and  the  dr«oping  of 
the  arms  aborally*      vhen  put  back  in  the  dish  of  sea  water,   the 
animal  usually  walks  in  nearly  the  same  direction  as  before,     Thii 
persistence  of  direction  and  the  fact  that  the  tube  feot  are  quite 
retracted  after  each  step,    indicates  that  the  mechanism  of  retrac- 
tion and  extension,   of  which  as  we  h*ve  seen,    the  step  reflex  is  ft 
modification,   is,  perhaps,   in  no  way  dependent  upon  or  implicated 
in  the  mechanism  of  orientation*     The  only  point  of  contact  of  these 
two  mechanisms  is  the  fact  that  they  both  act  upon  the  tube  foot* 
In  the  locomotor  state  then  oveiy  tube  foot  is  oriented,  whether  it 

*t 

be  retracted  or  not,  but  retracting  and  extending  in  such  tube  feet 
are  accomplished  usually  as  parts  of  the  step  reflex* 


B3HAKING   UP  ££  TMS   SoORPlffATidD  BiPUL^   INTft 
AR^AS   IN  WHICH   ms   TUM   RCST  A!f 
IN 


Perhaps  the  most  puzzling  thing  about  the  unified  impulse 
is  the  fact  that  under  certain  conditions  it  may  be  broken  up  so 
that  it  may  exist  in  only  a  part  of  the  starfish,  or  tube  feet  of 
different  parts  of  the  animal   became     orientsd  in  different  direc- 
tions* 

Adapjtj.T;jeneja.js 

In  case  of  some  types   (Jennings  1907)  of  the  righting 
reaction,  and  in  going  around  an  obstacle  this  orienting  of 


«r 


•41- 

the  tube  faet  in  different  parts  of  the  starfish  in  different 
and  sometiijios  oppostie  directions  is  highly  adaptive  in  tint  it 
is  the  only  tray  the  aot  could  be  accomplished* 


Thus  in  the  above  diagram, fig*  14  w*iich  illustrates  a 
frequently  observed  type  of  righting  jpeaotion  the  rays  labeled  a,  & 
have  doubled  under  and  ire  migrating  in  th<j  direction  of  the  arrow* 
The  raya  labeled  o.  e,  under  the  influence  of  the  same  unified  Impulaa 
have  turned  in  the  same  dir action  but  migrate,  aftsr  having  turned,    in 
the  opposite  direction,    thus  crossing  over  the  am*  a.  lj>  and  complet- 
ing the  somersault*     As  soon  ms  the  righting  is  complete  the  rays 
o.  2  *£  th«  ABM>  direotion  as  the  rays  a.  b. 


t~ 


the  swirfi^  ««•  in  position  1  it  *as  mov- 
ing in   tha  direction  of  th«T  arTO1*  and  all  of  the  tube  feet  were 
oriented  in  this  direction.     However,   when  coming  up  against  the 
obstacle   (3)    the  tube  feet  of  each  ray  immediately  changed  their 
orientation   to  the  direction  indicated  by  the  arrows  at  the  tips  of 
the  respective  rays.     This  results  in  the 


h»I 


^ 


• 


-42- 

animal  neatly  avoiding  the  obstacle  and  migrating  off  in  the 
direction  indicated  by  the  upper  arrow.  This  is  a  very  interest- 
ing reaction  and  has  been  made  the  subject  of  careful  study  below 
in  an  effort  to  discover  the  factors  concerned  in  this  breaking  up 
of  the  coordinated  impulse* 

Mangold  (1908)  has  described  an  observation  in  the  slen- 
der armed  Luidia  ciliaris  in  which  the  animal  was  seen  to  have  an 
arm  bent  so  that  coordinated  tube  feet,  all  extending  in  the  same 
direction,  were  some  extended  out  to  the  right  of  the  ray,  some 
parallel  wi  th  the  ray  and  some  to  the  left  of  the  ray. 

If  we  are  to  explain  this  very  puzzling  behavior  from  a 
physiological  standpoint  we  can  not  merely  point  out  its  adaptive 
or  regulatory  value,  we  must  attempt  an  analysis  of  iti  mechanism. 
It  is  futile  also,  to  conjure  up  a  complex  "center"  in  the  nervous 
system  which  acts  as  eoordinating  mechanism  or  presiding  regulator, 
orienting  the  tube  feet  of  various  parts  of  the  body  in  such  a  man- 
ner as  to  best  accomplish  the  act  of  the  moment.   Ste iner  (18 98^ 
hypothesizes  a  "righting  center"  and  Preyer  (1886)  "centers"  for 
various  activities*  There  is  no  structural  basis  for  such  an  assump- 
tion #  and  it  is  not  in  accord  with  observations  on  the  behavior  of 


#  Spix,  (1809)  described  a  nervous  system  for  the  starfish  that 
would  satisfy  such  an  assumption.  Unfortunately,  ,however,  it  proved 
to  be  the  system  of  gastric  and  hepatic  mesenteris  filaments. 

Acceding  to  Baudelot  (1872)  who  gives  an  historical  resume  of 
the  earlier  morphological  literature  the  subject  became  so  oontrover- 
sal  that  A.  H.  Quatrefages  (1842)  made  the  statement  freely  trans- 
la  tad  as  follows.   "Naturalists  of  great  merit  have  come  to  such 
diverse  conclusions  as  to  the  significance  of  the  various  systems 
of  (Bchinoderm)  organs  described  as  nervous  in  function  that  I  have 
decided  to  remain  in  this  regard  in  a  state  of  philosophical  doubt." 


•v  II 


•aiej'i 

901 


-rsrifc 
£)  lo 


-43- 

the   tube   feet  which  seem  to  indicate   that  they  all  act  very  much 
like  their  neighbors,    but  with  too  much  independence  to  lead  to  the 
belief  that  they  are  subject  to   the  control  of  a  higher  center.     Tube 
feet  act  only  in  response  to  stimuli  which  affect  them  or  spread  to 
them  from  neighboring  tube  feet, 

Possible  physiological   explanation   in  the  traction  on  the 
tube  feet  resulting  from   the  movement  of   the  rays  over  the  substrate, 

It   seams   to  me    that  the  only  constant  factor   that  could  ac- 
count for  the  behavior  observed,    is   the   traction  of  the  substrate  on 
the  tube  feet.        This  traction  is   the  mechanical  result  of  the  move- 
ment of  the  starfish  over  the   substrate,    (See  Cole  1913lr), 

Thu^B  Mangold's  starfish   (fig,        )   is  moving  in   the   direction 

of  the  ant>w.      The  various   tube  feet  may  receive   stimuli   from  the  aub- 

I  ***i 

vx  <y 

strate  which  result  in  their  orienting  this   direction. 

Similarly  the  righting  starfish  has  set  in  action  by  the 
activity  *£  the  rays  a  and  b_  (fig.   14)  a  somersaulting  motion  on  a 
horizontal  axis.      This  results  in  pulling  the  rays,    c  and  e  in  the 
direction  of  the  arrow  tnat   indicates  their  motion.      It  is  this  trac- 
tion that  may  orient  the  tube  feet.      In  this  connection  it  is  to  be 
noted   that  if  the  rays  o  and  e  do   not  droop  down  to   the  substrate  but 
are  carried  over  at  a  level  of  or  above  the  disk  (  as  is  more  often 
the  case)    their  coordinated   impulse  does  not  reverse  but  remains, as 
indicated  by  the  parallel  extension  of   the  tub«  feet, in  haroiony  with 
that  of  the  rest  of  the  animal. 

In  the  case  of   the  deviating  starfish,    the  axis  of  the  rota- 
tion that  is   involbed  in  the  avoiding  erf  the  obstacle  is  of  course  the 
obstacle  itself.      There  is,    in  th«  progress  of  the  reaction  first  a 
pushing  against  the  obstacle  which  involves  cessation  of  locomotion  on 
the  part  of  the  rays  on  one  side  of  the  body,    but  its  continuation 
(  or  quick  resumption  after  temporary  cessation) 


•  44  * 

on  the  other,   perhaps  the  stronger,    aide.     A»  this  continues, 
due  to  th«  comparative  rigidity  of  the  animal,    there  10  a  pull 

(h1^ 

in  the  direction  of  the  arrows   (at  the  tips  of  the  rays)   to  which 
pull   the   tube  feet  seem  to  coordinate  themselves. 

Direct  pull,   exerted   throu^i  the  substrate  by  the  movement 
of  the  animal  and  acting  on  the  tube  feet,   can,assuming  that 
it  orients  then,   account  for  the  above  described  behavior.     We 
•nail  now  turn   to   the  evidence  for  and  against  the  contention 
that  the  pull  of  the  substrate  does  orient  the  tube  feet* 

Direct  evidence  invoonsluBive. 

The  obvious  way  of  testing  this  is  to  slowlynpull   the  animals 
over  the   stubs tra to   (see  Cole  1913&)  and  ascertain  whether  a 
tendency  to  locomotion  in  this  direction  could  be  built  up* 
About  forty  treats  were  made  with  rigid  non-looomotor  animals* 
The  tube  feet  at  first  caught  hold  and  clung  to  the  substrate* 
This  became  less  and  less  manifest  and  the  rigidity  of  the 
myodermal   sheath  gave  place  to   the  flexibility  that  usually 

M* 

accompanies  locomotion*     Locomotion  followed,   however,  less   than 

s^> 

half  the   trials,    the  animal  more  often  settling  down  obstinately 

Tt>  W  H/cf} 

in  the  place  it  was  pushed  t*. 

o 

•Shen  the  locomotion  did  fallow  it  was,   unfortunately,    in 
every  case  but  one  in  the  QPPO gi te  direction  to   the  puXl.       It 
continued  for  a  few  cm*  only,   <ahen   the  animal  would  settle  down  into 

the  rigid  state.     The  one  animal  that  crawled  in  the  direction 

it 
fe*  was  pulled,    continued  to  crawl  all  day* 

These  results  were  complicated  by  the  effects  of  contact 
stimulation  of  the  dorsal   surfaces  which  induces  close  attachment 
and  cessation  of  locomotion.   Hie  reactions  of  the  animals,    then 
for  the  most  part  may  be  considered  a  result  of  this  stimulation 
rather  than  a  result  of  the  pull. 


. 


.    •• 


-45- 

X  have  in  fact  been  unable  to  manipulate   the  starfish  so 
as   to   exert  a  steady  pull   in  any  one  direction   for  any  length  of  time 
without  causing  the  tube  feet  to  attach  and  hold  on,   a   tendency  -which 
then  spread   to  other  tube  feat  and  inhibited  any  coordinated  impulse 
that  mi/7;ht  havo  resulted.      Later,   moraover,  on  certain  occasions  they 
have  been  observed   to  retract  and  be  entirely  inactive, 

I  h-jve  manipulated  the  animals  by  slowly  moving  the   sub- 
strates on  ^hioh  ona  or  two  rays  were  ?ra Iking  and  have  manipulated 
tha.-i  by  means  of  nourotoiaized  or  anaesthetized  rays  but  h^ve  not  been 
able   to   do    30  Tvi  th  enough  dalicaoy  to  avoid  stimulating   the   tube  feet 
to  become  attached  or  completely  retraotad,      I  ara  inolinad,    therefore, 
to  consider  those  results  irrelevant  rather  than  evidence  against   the 
possibility  thit   the  substrate  may  have  an  orienting  influence  upon 

the  tube  feet. 

W**t  \?'i 

IS vi dance   frog  neurotomizad  animals. 

I   f  the  substrate  can  orient  the  tube  feet  by  exerting  a 
directive  puXl  on  them  through  the  movement!  of  the  animal,  ^e  might 
expect   to  find   that  if  one  of  the  posterior  arms  of  a  loconotor  star* 
fish  -?ere  neurotoiaized,    tnere  might  be  coordination  brough  about  by 
the  factor  in  question*     Several  experiments  were  performed  with  it 
in  view  to  teat  this  hypothesis,    the  results  of  which  were  complicated 
by  the  marked   tendency  in  the  injured  animals  to  attach  closely  and 
firmly  to   the  substrate. 

The  operation  was  performed  on  a  large,   active  Pyonopodia* 
At  first  the  tube  feet  on  the  injured  ana  attached  but   the  movement 
of  the  animal  wrenched  the   tube  feet  loose  leaving  in  one  or  two  caae» 
the  dis."    affixed  to   the  substrate*     As  the  locomotion   continued   the 
tube  I3et  stuck  less  and  less 


)  I 

tightly,    until   they  behaved  very  much  like   they  do  in 
ordinary  but  rather  inictive  locomotion.      The  arm  being  very 
flexible,   coordination  did  not  occur  when  the  neurotoraized 
arem  *as  anterior,   because  it  bent  around  and  under  before   the 
tube  feet  let  loose.   Some   throe  or  four  tours    ;fter  the 
operation   the  tube  feet  in   the  nvuromo  tized  arm  were  all 
retracted  and   the  arm  practically  motionless.     A  week  later  the 
wound  seemed   to  have  healed  and   the  arm  to  hare  regained  its 
natural  movements. 

When  this  experiment  was  repeated  on  Pisaater.    the  animal 
remained  stationary  for  fiw«  minutes,    the  neurotoraized  ray, 
affixing  itself  rather  firmly  to   the  substrate*     A*  the  end 
of  this   time  the  other  rays  were  seen  pulling  in  the  direction 
of  their  former  anterior,  away  from  the  neurotomized  ray.     Some 
refractory  tube  feet  were  seen  attaching  to  the  substrate,   which    / 
were  wrenched  off  by   the  activity  of  the  uninjured  arms.     One 
left  Jte  disc  behind.     Refractory  feet  became  fewer  and  loss 
refractory.     In  one  minute  coordination  was  complete,    though  not 
very  active.     The  animal  walked  quite  rapidly  the  length  of  the 
aquarium.     Locomotion  seemed  normal  except  that  the  nsurotomized 
arm  was   contracted  and  rigid.     It  was  always  behind  or  obliquely 
behind  in  locomotion* 

It  might  seem  possible  therefore  that  coordination  of  the 
tube   feet  is  not  wholly  dependent  upon  the  presence  of  an  insect 
nervous  system*     If  such  stimuli  as  cause  the  attaching  reflex,  are 
carefully  excluded  coordination  may  be  established,   across  a      -ut 
nerve   cord  by  the   traction  of  the  other  anas. 

When  the  neurotomized  starfish  had  tone  to  rest  it  was 
observed  that  the  four  intact  rays  were  stationary  while  the  neuro- 
moized  ray  walked  xautit  about  in  the  sector  between  the  adjacent 
stationary  rays. I  Eion  prodded  the  starfish     and  threw  it  into  a 


as 


-47  » 

vary  intenaly  appreaeed  atato.     The  neuro  tomized  ray  continued 
a  a  before  actively  moving  in  its  own  sector.     The  gilla  were 
retraoted  and  tho  pedioellariae  open,   OTer  the  whole  atarfiah 
while  in   the  region  of  the  out  and  beyond  the  gills  were  out 
normally  and   the  pedioellanae  at  reat.     On  prodding  the  neurotomiaed 
ant  the  gilla  drew  in,   the  pedioellanae  stood  out  and  opened 
and  the  tube  feet  held  fast.     This  last  reaction  paaaed  off 
and  the  noufcotomized  arm  started  locomotion  again  in  ita  aeotor. 
The  gilla  and  pedioellaria  remained  in  the  irritated  state  so 

that  the  out  did  not  deraark  two  different  areas  of  gilla  and 

and 
pedioellaria  aa  it  had  before/<*s  it  did  now  with  the  tube  feet* 

X  believe,    therefore,    that  neural  oonneotion  for  the 
apreading  of  an  Impulse  aoroaa  the  out,   either  through  the 
dermal  nerve  net  or   through  an  unout  portion  of  the  ambulaoral 
oord,   was  entirely  absent. 

The  eaaentials  of  these  eaperiments  were  repeated  on  a 
nuaber  of  animals,     with  very  similar  resulta.       Asterina 

responds  in  thia  way  but  rather  less  completely  than  Pisa a tar. 

\r\  w  f?o~ 
An  active  atarfiah  with  a  e     anterior  (aee  pr"T*5) 

wma  picked  up  quicly  and  the  raya  bod  neurotomized*     The 
animal  was  aet  on  the  aide  of  the  aquarium  with  the  intact  raya 
(a  •)  directed  downwards.     Locomotion  followed  a  e  down  the  aide 
and  across  the  aquarium.       S  e  d  presented  refractory  tube  feet 
and  locomotion  was  jerky  as  these  tube  feet  were  pulled  loose. 
Later,   when  the  animal  had  progressed  about  6  cm  coordination  waa 
fairly  well  established  but  not  very  active.     Aa   the  refractory 
tube  feet  were  pulled  loose  they  retracted  and  did  not  react  at 
ally   for  sometime.     Neighboring  tube  feet,  however,    showed 
diminished   tendency  to  attach  tightly  and  were  more  apt  to 
coordinate.     Locomotion  waa  alow  at  first  but  later  more  rapid. 


•  i  ••;•  **  h 


f.' 


-48- 

(-near  the  ta»O 

X  next  neuro tomi xed ^ea oh  arm  of  a  rather  large  starfish  that 
was  not  very  active.     X  "started"   it  on  the  side  of  the  aquarium 
vath  ita  former  "anterior"  downward.     Locomotion  continued  down 
the  aide  until   the  disc  was  about  at  the  angle  of  the  wall  with 
the  floor  of  the  aquarium*     At  this  point,    the  animal  assumed  the 
rigid  state  and  would  orawl  no  farther* 

This  experiment  was  repeated  on  a  amaller  and  more  active, 
specimen.       Locomotion  down   the  side  was  more  active,    the 


(former  anterior)  arm*  taking  up  the  locomotion  quickly  and  by 
pulling,    in  harmony  with  the  force  of  gravity,   forced  aoertain 
amount  of  coordination  in  the  other  rays*     There  were  a  few 
refractory  tube  feet  in  each  of  the  rays,   each  ray  shwwing  a 
tendency  to  migrate  toward  its  own  tip*     3hen  the  animal  reached 
the  angle  of  the  side  with  the  floor  of  the  aquarium  the  locomo   • 
tor  impuloe  was  so  well  established  that  crawling  continued 
across   the  floor  of  the  aquarium  and  up  the  other  side*         If 
an  obstacle  such  as  my  finger  was  placed  between  the  two  anterior 
rays  and  held  stationary,    two  responses  were  observed*     In  two 
oases  a  normal  deviation  reaction  ensued,  but  the  more  frequent 
result  was  a  stoppage  of  locomotion  followed  after  a  variable 
length  of  time  b£  a  resumption  of  locomotion     in  some  other 
direction* 

The  starfish  wa*  then  taken  up  and  stimulated  harshly  on 
the  various  rays*     The  animal  assumed  tho  rigid  state  -then  set 
down  the  tube  feet  being  tightly  attached,   and  remained  in  this 


state  for  some  time*     The  rays,  that  became  active  first  were  not 
contiguous,  X  -a«4-o,  while  b  d  and  e  remained  attached*     A  and  o^ 
moved  a  out  in  their  sectors  at  random  all   the  afternoon*     The 
next  raoraing  the  starfish  was  in  a  mo  rib  und  condition  but 
had  migrated  across  the  aquarium  during  the  night* 

The  essentials  of  these  experiments  were  repeated  many 


.-     • 


- 


..-49- 


times  with  results  thatvaried  between  the  two  examples  cited* 
It  was  found  that  if  the  manipulation  was  rough  or  unnecessarily 
prolonged,    the  animals  would  become  rigidly  attached  and  would 
not  locomote  for  some  time  or  at  all  while  some  animals  refused 
to  coordinate  with  even  the  gentlest  manipulation*^ 

#  Opinion  on  the  necessity  of  an  intact  nervous  system  for 
eohinoderm  coordination  seems  divided.     Romanes  and  Jfiwart  (1881) 
and  Cole  (1913)   record  some  slow  coordination  between  parts 
on  opposite  sides  of  a  cut  in  the  nervous  system,  while  Husso 
(1913)  believes  that  coordination  may  be  absolutely  normal  with 
the  oral  nerve  ring  removed,     Tlark  (1890)   states  that  the 
movements  of  the  tentacles  in  Synapta  and  coordinated  movements 
of  the  body  muscles  are  not  destroyed  by  cutting  the  nerve  ring* 
See  also  Grave  jqoo  on  Qphuira  breviepina 

Among  those  who  report  the  opposite  results  are  Vulpian 
(1862)   ,:rukeuberg  (1881)  DeMoor  an*  Ohapeaux  1891  Loeb  (1900) 
Mango  lr  (Wow  i4W )   fJtoore  (19100,  1910te)  ete 

Trom  these  experiments,   and  those  on  trie  righting  of 
neurotomixed  animals  which  will  be  described  later,   I  think  that 
it  can  be  safaly  concluded  that  while  there  is  no  neural  or 
•neuroid"   (Parker  191$}   transmission  pastja  cut  in  the  am  »ulacral 
nervous  system,    there  may  be  a  certain  limited  amount  of  coor- 
dination between  parts  separated  by  such  a  cut  brought  about 
-mwfafiHe***  through  there  mutual  relationships  to  ehe  substrate* 

yridenoo  froyi  the  behavior  oj[  ffie  animal  when  its,  part? 
aye  placed  on.  aet^rftte,  pnubst rates,.' 

We  shall  turn  now  to  such  indirect  evidence  as  bears  upon 
this  point  from  the  behavior  of  an  animal  on  separate  substrates 
andAa  quantitative  analysis  of  the  mechanics  of  the  deviation 
reaction.     'Uiese  methods,    though  indirect  do  not  cause  the 
attaching  reaction* 

The  rays  of  an  active  starfish  that  is  not  in  the  coordinated 

as 
state, /has     been  seen  above  will  migrate  toward  their  tips,   into 

free  floating  glass  tubes*     If  however  before  suspending  and  before 
the  floats  are  presented  to  the  r«y«.    «*•  anim  al  *»»  in  *  §teu 


•50   • 

Of  active  locomotion,    the  rays  that  were  anterior  will  crawl 
on  into  the  tubes  while  the  ray»  that  were  posterior  will 
start  to   crawl  out  of  them*     Usually  before  one  of  these  rays 
f  leaves  go  its  hold  on  the  float,   or  at  any  rate  soon  afterward, 
the  impulse  in  thia  ray  is  reversed  and  it     la  aeen  to  be 
active  in  its  migration  toward  its  own  tip,   regardless  of  the 
direction  in  which  the  other  rays  are  crawling.     If  now  the 
tubes  are  removed  from  their  floats  and  set  on  the  bottom  of  the 
aquarium,    -vith  the  tip  of  a  ray  in  each,    the  coordimt  i  impulse 
is  quickly  re -established  and  the  animal  migrates  back  ad  forth 
within  the  confines  set  up  by  the  ends  of  the  tubes*     After 
extensive  experimentation  with  the  reactions  of  Pisaster  in 
these  floats,   I  have  very  seldom  seen  the  unified  impulse  appear 
when  the  floats  were  free  to  move  separately,   and  having 
appeared  it  seldom  lasts  more  than  a  minute  or  two*     It  appears 
quite  promptly  and  lasts  for  a  long  time   (  an  hour  or  more) 
if  the  tubes  are  not  separately  moveable  but  are  resting  on  the 
bottom  of  the  aquarium* 

Supplementary  experiments  were  carried  on  with  flat  free 
swinging  substrates*     One,   two  or  three  of  the  rays  were  put  on 
the  substrate  and  the  others  allowed  to  han^  over  the   iide  on 
the  floor  of  the  aquarium  half  a  cm*  below*     The  part,    on  one 
substrate  was  often  seen  to  migrate  while  that  on  the  other 
remained  stationary,  and  they  were  not  infrequently  seen  to 
migrate  in  different  directions.       Of  course  this  would  not  be 
likely  to  happen  if  the  substrates  were  not  separately  moveable, 

From  the  above  experiments  it  would  seem  that  a  factor  in 
the  unity  of  the  coordinated  impulse  is  the  unity  of  the 
substrate  or  rather  of  the  animals  relation  to  the 


/ 


•If 


-51- 


#  One  might  state  the  oase  rather  paradoxically  in  metaphysical  terms 
by  saying  that  the  animal* 8  soul  or  entelechy,  or  some  part  of  it  at 
least  resides  in  its  substrate.   (See  Dreisch  (1908)  Steme  (1891).) 

Therefore,  if  the  activity  of  the  animal  caused  the  substrate  to  move  in 
one  direction  with  reference  to  one  part  and  in  another  direction  with 
reference  to  another  part,  as  is  the  oase  in  the  righting  and  deviation 
reaction,  we  might  expect  that  the  unified  impulse  would  be  broken  up  in 
certain  detaitninate  way*. 

Deviation  reaction  not  interfered  with  by_  cutting  ne rvous  con- 
nections with  interradial  a rea » 

That  the  coordinated  impulse  is  thus  broken  up  by  mechanical 
traction  in  the  deviation  reaction,  is  made  likely  by  the  fact  that 
the  reaction  is  perfectly  normal  even  after  the  nerve  net  on  the  out- 
aide  of  the  epidermis  was  out  through  between  the  obstacle  and  the  am- 
bulaoral  nervous  system.  This,  of  course  prevented  any  stimulus  from 
the  contact  of  the  starfish  with  the  obstacle  reaching  the  tube  feet, 
but  did  not  affect  the  mechanical  factors  in  the  relation  of  the  sub- 
strate with  the  tube  feet.   It  is  therefore  to  be  concluded  that  these 
mechanical  factors  play  an  important  role  in  the  deviation  reaction. 

Deviation  reaction  not  elicited  by.  prodding  interradial  area. 
Moreover,  if  the  nerve  net  between  the  bases  of  the  two  an- 
terior rays  be  stimulated  by  jabbing  it  quickly  with  a  knife  or  a  blunt 
instrument,  the  deviation  reaction  w.ill  not  follow*  The  aniaal  will 
either  continue  undisturbed,  stop  and  then  continue  or  go  into  the  at- 
tached condition  and  remain  so  more  or  less  permanently.  The  first 
response  is  by  far  the  most  common  if  the  specimen  is  normally  active 
and  not  stimulated  too  harshly.   I  have  never  observed  a  marked  change  of 
direction  as  is  seen  in  the  deviation  reaction  to  say  noihing  of  the 


- 

-    JSi 


'.  Oil! 


. 


-52- 

ooaiplioited  coordination  cf  movements   thit  are  involved  in  the 
deviation  reaction* 

iMMlf^tn*^'y<*  aspects  pf  the  "deviation  push"  oji  different 
substrates  and  witft  different  feints  on  the  animal  vary  *ith 
mechanical  conditions  while   quantitative  aspects  olT  oontaot 
stimuli  required   to  initiate   the  negative  reaction  dft  not. 

It  was  thought  that  the  auount  of  push  which  the  deviating 
animal  exerted  upon  the  obstacle  -whenjoonsidered  in  oonneotion 
with  itB  pulling  Ability,    and  other  reactions  might  thro«  light 
upon  the  mechanisms  of  the  deviation  reaction.     The  amount 
of  push  was  measured  by  attaching  the  obstacle,   a  lever,    swinging 
freely  frofr  a  rigid  fulcrum     by  a  thread  to   the  recording 
spring  above  described*     The  push,    then  was  recorded  as  the 
height  of  the  curve,  written  on  the  slowly  revolving  drum*     The 
appearance  of  the  curve  was  as  below  for  the  different  species 
studied* 


The  push  continues  to  increase  until   t&a  deviation  begins,   that 
is,   until   the  effectors   (tube  feet  or  spines)  on  one  side  of  the 
body  begin  to  reverse  themselves  and  the  rotation  around  the 
obstacle  as  an  axis  is  initiated*     From  then  on  there  is  an 
irregular  decline  in  the  push  until  the  naoDdb  animal  is  free 
of  the  obstacle*     ith  the  drum  running  at  the  same  speed,    the 
shape  of  the  curve  as  well  ae  its  height  is  dependent  upon  the 
aotivity  of  the  specimen  studied*     This  was  taken  into  account 
so  as  to  get  results  as  comparable  as  possible*  If  The  sea  urchin 


1 1 roa/ry l o c en trp t e»p   franoisoanua  was  found  to  be  mowing  on  sand 
by  means  of  its  spines  only.     In  deviating  around  an  obstacle 


ttft  ol 


•I  fifti 


i 


14, 

. 


. 


^-i*S 


' 

"^  .«•: 


ll  le  MUHHI 


-53- 

it  takes   the  same  course  aa  a   starfish.      This  ease  is  oited  since  the 
spines  of  the  sea  urchin  do  not  attach  and  their  behavior  in  this  con- 
nection indio.itss  a  rathar  striking  similarity  between  the  physiology 
of  the  spine  and  that  of  the  tube  foot* 

The  value  of  the  "deviation  push*  of  this  specimen,    was  found 
to  average  15  g.      This  was   increased   to   17  g  when  a  load    (about  40  g) 
was  placed  on  the  dorsal   side  of  the  animal.      The  "pulling  ability"  was 
found  to   be    (average  of  6  trials)   10  g  unloaded  and  15  g  loaded.     Allow- 
ing for  a  certain  amount  of   fatigue  in   the  later  trials   the   "pulling 
ability"   was  found   to   be  approximately  equal   to   the  "deviation  push". 

The   same  relationship   seams    to  nold  with  Pyonopodia.     As 
seen  above  the  pulling  ability  averages  47  g.    the  deviation  reaction 
(average  of  four   trials  60  g  45  g  60  g  30  g)    is  48g.      These  are  in- 
creased  to  V2   and   105  g  respectively  by  loaning  the  animal  with  80  g. 
of  glass-flare*     If  the  animal  is  placed  on  sand  the  values  are  similarly 
related   to   each  otli.sr  but  are  reduced  as  follows*      Pulling  15  fim,    pull- 
loaaed  -with  80   gnu    32  gm,      deviation  29   gm,   deviation  loaded  35  cm. 

Due  to  the  fact  that  Pisa a tor  and  Asterjna  are  able  to  pull 
very  much  harder  in  proportion  to   their  size  than  are   the  sea  urchin 
or  Pyonopodia  and  since  this  pull  is  due  to  the  constant  increase  of  the 
attaching  tendency  correlated  with  the  pull,   we  find  that  the  deviation 
push  correlates  more  closely  with  the  pulling  ability  on  sand,   taking 
into  account  of  course  its  lesser  frictional   coefficient,    than  with  the 
pulling  reaction  on  a  solid  substrate*     The  average  deviation  push  of 
Pisaster   (about  15  cm  in  diameter)   is  20  g.   on  a  solid  substrate  and  6  g 
on   sanJ.      Agtarina    (8   cm)   on  a   solid   substrate  exerts  a  deviation  push  of 
4  gt    but   with  4  g.  weight  on  ita  back  this  is  increased  to  6  g.      This  is 
~*ith  the  pulling  ability  of  a   larger  specimen  on  sand  of  7.5g. 


- 


-54  » 

and  on  sand  weighted   (40g)  of  15  g   (See  p.   21).     The  above  study 
of  the  mechanics  of  the  deviation  does  not  pretsnt  to  be  statist!- 
oally  comprehensive.     The  objact  is  merely  to  point  out  that  the 
"deviation  push"  can  be  always  increased  bu  weighting  down  the  animal 
and  that  in  the  sea  urchin,  which  uses  its  spines,   and  in  Pyonopodia 
which  does  not  attach  tightly  while  pulling  hard   (Soe  p.  22)   the  pull 
oan  also  be  increased  by  weighting  down  the  animal.     The  relation* 
ships  of  pull,   and  deviation  push  in  the  loaded  and  unloaded  Asterijia 
and  i'isastar,   are  consistent  with  the  above  and  comparable,    quanti- 
tatively to  the  pulling  ability  of  the  animals,    both  loaded  and  un- 
loaded on  sand* 

Thus,   the  attaching  reflex  that  strangthens  with  the  resis- 
tance to   the  ordinary  step  (see  p.   19)  does  not  appear  comparably 
in  the  deviation  reaction.     This  it  seams  to  me  is  because   the  tube 
feat  on  one   side  of  the  obstacle  overbalance  in  their  traction  those 
on  the  other  side,    cause  a  rotation  of  the  animal   in  that  direction 
and  the  various   tube  feet  coordinate  in  the  direction  of  this  rota* 
tion.     There  is  than  no  resistance  to  the  step  bi'.t  merely  a  devia* 
tion  of  it  in  one  direction  or  the  other  brought  about  by  its  relation 
to   the  substrata* 

Another  fict  pointing  to  the  conclusion  that  the  factor* 
of  the  deviation  reaction  have  to  do  with  the  mechanical  relation* 
ship  of  animal   to  substrate  rather  than  with  reflexes  having  their 
receptors  at  the  point  of  contact  is  that  if  the  tips  (Asterina) 
of  the  rays  instead  of  the  dermi.  between  the  rays  com*  in  contact 
Tith  one  obstacle  connected  with  the  spring  recorder  the  amount  of 
pressure   that  it  takes   to  cause  a  change  in  direction,   does  not 
vary  if  »  weight  is  put  on   the  back  of  trie  starfish,     Xhe  value  it 
about  2.5  g  in  each  case*      This  shows 


-55-  •."«'  ,  5i 

as  might  be  expected  from  the  configuration  of  the  nervous  system,    that 
the  mechanism  of  the  deviation  reaction  is  altogether  different  from 
the  mechanism  involved  in  a  change  of  direction  rhen  the  tips  of  the 
rays  are  stimulated.      In  the  one  case  we  are  dealing  with  the  relatively 
constant  threshold  of  the  receptors  in  the  end  of  the  ray  while  in  the 
other  oase  we  are  dealing  with  factors  that  vary  with  the  mechanical 
data  of  load  and  friction. 

In  order  that  the  obstacle  may  be  left  behind  in  the  devia- 
tion reaction  there  is  usually  a  turn  of  at  least  70°  which  is  often 
recovered  from,   by  the  operation  of  a   tendency,   whose  mechanism  I  have 
not  worked  out,    to   continue  crawling  in  the  saue  direction  as  before 
the  disturbance,    even  if  the  action  involve  an  actual  change  of  direc- 
tion,  back,    from  one  assumed  as   the  result  of  the  disturbance*     This 
tendency  will  also  be  noticed  in  connection  with  the  righting  reaction 
(P. 75). 

COORDINATION  OF  MOV3lteNT8  OF  THiS   TUBfl  F&ST  WITH  TKOSB  OF 

THS  ABM  AS  A  WHO  18. 

Il.lus t ra t long o f  the  tendency  of  an  arm  to  set  itself  more 
ajt  right  angles  tp_  its  actively  .en-ten  teat  tube  feet,  when  such  move- 
ments involve  dorsal  and  vent ral  fle±ion  and  lateral  twisting. 

If  an  active  starfish  be  suspended  and  a  solid  object  be 
brou^it  in  contact  with  the  tip  of  one  of  the  rays,    there  will  be  a 
movement  of  the  tube  feet  in   the  direction 


•58- 


of  the  object,  an  activation  of  their  coordination  toward  the 
tip  of  the  ray*  This  will  bo  followed,  almost  immediately  by 
a  dorso -flexion  of  the  tip  of  the  ray*  She  ray  oan  be  said 

ywm&Ai 
to  set  ifaalf  more  nearly  at  ri^ht  angles   to  the  extended  active 

tube  feet*     This  reaction  has  been  observed  time  and  again  in 
fisaater  oraceuw.   Aaterina.   pyonopodia.    ?,eptaaterias«   i  a.  8 tor  bre- 
vi&inus  and  -.vaeteriaau  As  are  moot  movements 

of  the  animal   it  is  a  product  of  local  reflexes  in  that  it  ie  not 
dependent  upon  connection  with  the  oral  nerve  ring,   but 
occurs  equally  veil  in  active  isolated  arms. 


.   for  the  gentle  contact  we  aubatitute  a  harsh  tapping  of  the 
tip  of  the  ray,    the  tube  faet  will  retraot  and  the  ray  become 
more  rigid  and  shorter,     but  without  any  sign  of  the  dorsal 

flexion* 


w«  have  seen  that  if  a  tube  foot  in  the  middle  of  a  ray 

be  allowed  to  attach  to  an  objeot  and  the  object  be  then  pulled 

to  one  side,  the  tube  foot  with  it,  other  tube  fee*  will  alee 

•owe  to  the  sane  side  and  seemingly  reach  out  for  the  object 

to  which  the  tube  foot  is  attached*  Now  if  a  sufficient 

number  of  tube  feet  become  oriented  in  this  manner,  there  will  be 

a  lateral  twist  of  the  ray  toward  the  object*  Here  again  the 


•59- 

ray  oan  be  said  to  sat  itself  more  nearly  at  right  angles  to  the 
oriented  active  tube  feet  by  lateral  as  well  as  by  dorsal  movement* 


(See  also  Jennings  (1907)  description  of  the  taking  of  food  from  th« 
pedioellariae  by  the  tube  feet)* 

V-"    Hie  slender  armed  speoies  of  starfish 


trosohelii)  was  suspended  and  a  flat  piece  of  thin  celluloid  was  swung 
by  a  thread  to  the  ventral  side  of  one  of  the  rays.  The  tube  feet, 
oriented  rather  inactively  toward  the  tip  of  the  ray  immediately 

sieze  the  object  and  "walk"   it  in  the  direction  of  the  base*     This 

\ 
was  observed  to  involve  the  orientation  toward  the  object  of  quite 

a  number  of  tube  feet  both  above  and  below  it  and  the  bending  of  the 
ray  so  as  to  receive  the  object  in  a  sort  of  hollow*     The  tube  feet 
In  actual  contact  with  the  object  are, 


of  course,  undergoing  the  step •reflex,   but  above  and  below,  where 
the  tube  feet  are  all  directed  toward   the  object,   it  oan  be  said, 
•gain  that  the  ray  tends  to  set  itself  more  at  right  angles  to  aotive< 
ly  oriented  tube  fe-st,   this  time  involving  both  dorsal  and  ventral 
flexion*     In  the  region  where  the  tube  feet  are  undergoing  the  step* 
reflex,    there  is  no  bending  of  the  ray»# 

#  It  has  been  shown  by  both  Jennings  (1907)  and  Mangold    (1908«) 


' 


•60* 

that  as  the  tuba  feet  carry  a  small  pieee  of  food   toward  the 
mouth  there  is  a  "humping  up"  of  the  ray  in  the  region  of  the 
food  which  probably  involves  the  factors  desoribed  above.     The 
behavior  of  the  tube  feet  when  the  animal  moves  its  arm  in 
under  the  disc  as  a  part  of  the  food  taking  response  (Jennings 
1907)  would  be  interesting  but  Z  have  never  been  able  to 
induce  this  response  in  the  species  at  hand* 

Van^ral  flexion  pj[  ri.'did.of  loured  and  nicotinlzad  starfish/ 
If  a  Piaaster  in  a  state  of  extreme  rigidity  be  inverted 
there  will  be  as  we  have  seen,  a  rather  inactive  extension  of  the 
tube  feet  more  or  less  at  right  angles   to  the  rays*     There  will  be 
no  orientation  of  the  tube  feet  at  the  tip  in  the  direction  of 
the  ray*     The  rays,   soon  after  inverting  will  lift  themselves 
orally  and  assume    a  very  symetrioal  ventral  flexion*     This 
state  may  continue,  in  absenoe  of  disturbing  stimulation  for  as 
much  as  twelve  hours*     If  the  radial  nerves  be  out  or  injured 
near  the  base*   this  ventro  flexion  is  apt  to  be  very  ouch 
intensified  *o  that  the  steps  of  the  rays  come  nearly  or  quite 
in  contact  and  the  animal  assumes  what  Roman**   (i£3Xt    and 
ftfart  (1881)  who  describe  this  response  aptly  call  "  a  tulip  lite 
fora"*     This  is  similar  to   the  state  of  ventro  flexion  which 
Moore  (I920a^  #  describes  as  a  result  of  nicotine  poi»oning,  and 

/  The  effect  of  nicotine  on  starfish  had  been  desoribed 
previously  by  Preyer  (1886)  and  Greenwood  (1890) 


wfcioh  Z  have  confirmed  for  Pisaster,  lh«  chief  difference  seems 
to  be  that  the  tube  feet  in  the  nice  tini  zed  Pfrsastar  art  completely 
retracted,  while  those  of  the  rigid,  or  of  the  nourotomized 
animal  show  a  certain  amount  of  extension  but  no  particular 
orientation.     !Ih«  strength  of  the  spasm  is  greater  in  the  nico- 
tinized  animal  ffcsw. 

These  movements  are  shown  by  the  isolated  ray  from  both 
the  niootinized   (Moore)  and  the  rigid  animal* 


MM0 

JC         jnt  *df  a*  tfvjuru 


.sro/s  «* 


nB 


. 


HNt*  n^VM    JB  VWR      f 

. 


t»*(wr- 


-61- 

Deaoription  of  various  other  oorrelatgd  movements  o_f  the 
tube  feet  and  2JS&* 

If  an  aotive  Pisaster  be  suspended  in  -water  and  away  from 
contact  stimulation,    the  rays  move  about  for  a  while,    flexing  them- 
selves doraally  and  laterally,   in  m  manner  that  we  shall  discuss 
latar,   but  eventually  assume  a   state  of  vantro -flexion  similar  to 
that  assumed  by  the  rigid  animal*     The  aotive  animal  in  vsntro  flex* 
ion  differs,  however,    from  the  rigid  or  the  niootinized  animal  in 
that  contact  stimulations  at  onoe  set  up  activities  of  the  tube  feat 
and  arms*      The   tube  feat  raaot  positively  to  gentle  contact  stimula- 
tion and  retraot  upon  sever*  stimulation.     We  have  followed   the  im- 
mediate responses  of  the  anas  to   these  stimulations,   but  the  positive 
and  negative  activities  of  the   tube  fset  spread  to  the  tube  feet  of 
the  rest  of  the  animal,   as  also  do   the  corresponding  movements  of 
the  arms*     'ihus  if  the  stimulation  be  quite  harsh  the  tube  feet  will 
retraot  over  the  wnola  animal  and  the  arms  themselves  will  become 
shorter  and  more  rigid* 

In  oonneotion  with  the  positive  response  of  the  tube  feet, 
ir  will  be  remembered  that  this  does  not  spread  as  well  when  the  tube 
feet  are  free  from  contaot  as  it  dies  when  they  are  executing  the 
step  reflex*     A  weak  positive  response  theo,   such  as  the  positive  dif- 
ferential activity  of  the  unstimulated  anas  in  case  of  a  harshly  »tim- 
ulatad  animal,  hardly  makes  itself  notiovable  in  the  suspended  animal 
as  it  does  in  the  ae&ativt  response  of  the  animal  locomoting  on  a  sub- 
strata* 

Ascription  oj;  th..a  formation  ££  the  coordinated  jlmpulse  Tyhen 
the  tuba  feet  are  free  o£  the  substrata* 

A  strong  positive  response,  on  the  other  hand,   does  spread, 
and  in  spreading  involves  movements  of  the  arm,   as  the  following  ex- 
periment will  show.     An  aotive  Pieaster  suspended  and  in  a  state  of 


At 


•  £••?  -art*  c  .  t,! 

It 


»t    *«-• 

'• 


•CiJ 


.OtfOt^Mf^^    yjj    10    Itf 

*   a-."-       ,  .eB'jc^afci  avi.  .  A 


/  16  aide  of  the  aquarium  no 

3h^th«  will.       She  tube  feet  at 


tretched  out  toward   the  wall, 
tatfish  still  farther  over 
V__--  rays  a  e     nexed  dorsally  and 

began  migrating  in  their  own  direction.     In  the  meantime  the 
coordination  of  the  tube  feot  had  spread  so  as   to  include  all 
the  extended  tuba  feet  in  animal,  which  were  soon  all  pointed 
directly  toward  the  wall  of  the  aquarium*     As  the  tube  feet 
became  oriented  in  this  direction,   there  was  a  coordinated 
movement  of  the  rays.  Hay  £  twisted  to  the  left  and  bent  over 
toward  the  wall,    ray  &    twisted  to   the  right  and  bent  over  to 
the  wall  and  ray  g    bent  directly  over  the  disc  toward  the 
wall,     isacfli  ray  was  seen  to  set  itself  more  at  right  angles  to 

Cnin^j^i^d 

the  actively  -extended  tube  feet  whiOh  had  become  coordinatedly 
pointing  toward  the  wall* 

As  the  rays  a  e  continued  their  activity,   the  disc  was 
brought  closer  to   the  wall  and  with  it,    the  other  arms*     As  they 
touted  the  wall,    since  the  tube  feet  were  oriented  in  the  direo- 


tion  of  a  e  beaan  executing  the  step  reflex  in  this  direction 
and  the  animal  started  perfectly  coordinated  and  normal  locomotion 
in  the  direction  of  ft  e  (the  suspending  thread  having  been  out) 
go  rr  elation  oj£  these  movements  with  the  rj.ffrtinff  reaction* 
The  *ove  experiment  is  merely  a  simplification  of  the 
righting  reaction  of  the  uncoordinated  active  Pisaster.     If  we 
assume  that  two  adjacent  rays  initiate  the  reaction  by 
attaching  to  the  substrate  with  their  ventral  sides  turned  toward 
each  oth^r,   the  above  description  will  fit  the  rioting  reaction 
with  the  change  of  only  a  few  words.     The  same  dorsal  flexion 
of  the  initating  rays  and   their  migration  toward  their  tips  will 


4W»f$ 


-83- 


be  observed.     Tna   tube  feet  will  alljooordinate  pointing  in  the 
direction  of  the  initiating  rays  and'  the  other  ray  a  will  move 
so  as  to  oome  more  at  right  angles  to   tho  direction  of  the 
tub*  feet.     The  <aim  on  the  right  will  twist  to    the  right,  Tnd 
more  over  in  the  direction  of  the  initiating  raya.     The  ana 
on  the  left  will  twiat  to   the  left  and  do   the  same  tiling*     ihe 
arm  directly  opposite  the  initiating  arms  will  bend  directly 
over  the  disk  and  complete  the  somersault  with  locomotion,   as 
ws-  shall  show  later,    continuing  generally  in  the  direotion  of  the 
initiating  rays*     This  as  we  ahall  see  is  perhape  the  moat  common 

method  of  righting  it  tho  disposal  of  the  starfish* 

ing 
Analysis  ojf  Penning* a  Seven  types  of  Hjgh/f  reaQi.ion* 

Jennings  (1907  pp.  125»g  ff  }  however,   describes  seven 
•sin  ty]MM  about  which  the  extremely  variable  righting  reaction 
may  be  grouped.     The  first  type  is: 

l.*The  simplest  and  neatest  method  is  the  following*     X*o 
adjacent  rays  twist  their  tips  in  suoh  a  way  that  the  ventral 
surface s  of  the  two  face  each  other*     'Ihen  the  tube  feet  of 
these  rays  attach  themselves  and  throw  the  starfish  over  in  a 
neat  somersault** 

This  is  essentially  the  method  described  by  me  above* 
Jennings  description  leaves  out,   hare,    the  coordinated  action 
ef  the  unattached  arms  thou^i  he  mentions  it  elsewhere  in 
general  terms,   and  he  does  not  recognize   the   aprea^  of  the 
coordination  among  the  tube  feet  nor  its  relation  to  the 
movements  of  the  arms*     As  above  stated  this  is  the  commonest 
method  of  turning*       We  shall  inquire  as  to  the  reason  for  the 
turning  of  the  rays  toward  each  otfesr  in    a  majority  of  oases 
in  connection  with  our  discussion  of  the  righting  of  the 
oriented  starfish* 


-64- 

Jennings  sooond   type/i*  ae  follows, 

2.  *2he   tips  of  the  two  adjacent  rays  may  so    twist  that  tha 
ventral   surfaces  do  not  faoe  eaoh  other,   but  both  faoa  in  tha 
same  direction.      The   tube  feet  then  take  hold  and  thro*  the 
starfish  over,    twisting  it  about  an  axis  x*  whioh  passes  length- 
wise through  one  cf  the  attached  rays*     this  method  of  turning  is 
extremely  difficult  end  awkward  but  is  seen  at  time.       Usually 
however  ***>    a,  third  ray  takes  hold  and  aids  in  the  turning, 
the  method  then  forming  a   transition  to   that  given  next** 

I  have  observed  this  method  of  righting  only  a  few  times,  and 
variations  of  it  (Type  5   (6)  of  Jennings)  where  only  one  ray 
attaches  a  few  times  also*     In  eaoh  case  the  coordinated  impulse 
could  be  seen  to  spread  froxa  the  initiating  ray  or  rays  and 
involve  coordination  of  the  rest  of  the  tube  feet  and  to   some 
extend   the  arms  in  the  manner  described  above*     She  ray  that  might 
be  expected  to  attach  coordinately  (facing)   the  ray  that  bends 
down  is  usually  seen  lifted  above  the  substrate  and  reaching 
out  in  the  direction  of  the  righting*     Locomotion  after  righting 
is  usually  toward  the  rays  that  initiate  the  reaction* 

Jenning*s  thr$d  type  is  as  follows* 
3,*?hree  adjacent  rays  attach  and  remain  attached,   all 
pulling  throughout  the  reaction*     Usually  the  animal  turns  pri- 
marily by  the  aid  of   the  t**o  outer  rgfcs,  while  the  middle  one 
is  relatively  passive  and  compelled  to  double  back  under  as  the 
araimal  turns.     Often  this  middle  ray  walks  backward  beneath  one 
of  the  other  rays,   or  the  otfcer  walks  actively  over  its  surface, 
or  there  is  a  combination  of  these   two  movements   tillthe  normal 
position  is  reached:,        (  A  model  of  the  starfish  in  paper  or 
cloth  will  make  clear  the  necessity  of  such  movements  when 
three  of  the  rays  remain  atvtohed^" 

'.mere  is  no  new  principal  involved  here,   except  that  of 


•  .c 

•, 


•66- 

O) 

the  passive  movement  of  the  middle  x    ray  which  will  be 

A 

discussed  in  connection  with  the  fourths   type*      ifte  impulse 
spreads   to   the  tube  feet  of  the  two  unattached  rays*     The 
coordination  of  these  is  followed  by  their  raising  up  over  the 
diso  and  moving  toward  the  initiating  rays  in  the  Mae  way  and 
according  to  the  same  principles*  as  described  above* 
(types  1  and  2), 

The  fourth  type  is  as  follows* 

4.  "Four  of  the  rays  take  hold,    two  extending  to  the  right, 
two  to   the  left.     Then  the  fifth  ray,    (which  we  nay  eall  the 
posterior  one)  is  lifted  straight  up  and  swings  directly  over 
till  its  ventral  surface  reaches  the  bottom,  while  the  anterior 
attached  pair  walks  backward  beneath  the  posterior  attached 

pair  the  latter  walking  forward  over  the  surface  of  the  (former)" 

f-M  if 
mis  type  of  righting  is  sketched  en  p.  In  oase 

of  Plaaster  it  is  more  apt  to  scour  if  the  animal  is  very  much 
relaxed*     The  sequence  of  the  events  as  I  have  observed  it  is  as 
follows.     The  anterior  rays  twist  toward  each  other  and  the 
coordinated  impulse  spreads  over   (or  is  already  in)  the  starfish 

a*  in   type  !•     This  results  in  the  twisting  toward  them  of  the 

p*t 
lateral   rays  and  the  bending  up  of  the  posterior  ray*  fate  to 

the  relaxed  state  of  the  starfish  ersoroe  other  physiological 
factor  which  prevents  the  lateral  arms  assuming  their  usual  state 
of  ventro  flexion,    these  droop  to  the  atubstrate  and  become  the 

e,e 
"posterior  attached  arms"   (rays  fc  in  fig]1*)  •       How  the  fadtor 

which  causes  the  moving  forward  of  the  back  rays  xhen  the  direc* 
tion  of  the  coordinated  impulse*  as  seen  by  the  activity  of  the 
Initiating  rays  causes  locomotion  in  the  opposite  direction  is 
the  same  factor,   X  think,  which  amuses  the  complex  coordination 
of  the  deviation  reaction,     I  have  presented   the  evidence  which 
leads  me   to   think  that  the  factor  in  question  has   to  do  with 


•66* 

the  relation  of  the  moving  parts  of  the  animl  to   the  substrate  and 
a  consequent  orientation  of  the  tube  feet  in  the  direction  tf 
the  movement* 

Jennings  fifth  type  is  as  follows: 

(4)   6*  All  of  the  rays  attach  themselves.     How  the  turning 
can  be  accomplished  only  by  the  release  of  certain  rays,   ihen  the 
Method  passes  to  one  of  the  types  already  described* 

The  method  of  release  as  I  have  observed  it  is  of  two 
kinds*    (!)   'i3ie  pull  of  the  other  parts  of  the  starfish  tear  loo  so  ^ 
attached  tube  feet*     These   then  retract  and  other  tube  feet 
attach  but  usually  not  so  tightly  as  those  that  were  first 
attached*         As  this  continues  the  tube  feet  in  the  region  in 
question  either  all  become  retracted  and  the  ray  is  pulled  free 

(2) 

of  the  substrate  and  swung  over  in  the  righting,  «*  the  tube 
feet  become  oriented  in  the  direction  of  the  pull  and  righting 
proceeds  according  to  method  three  or  four  with  possibly  a 

(r.e(e«»«A) 

lifting  of  the  looonotor  ray  free  of  the  substrate* 

A 

Jonninge  sixth  type  has  already  been  described  in  connection 
with  his  second  type* 

Jenning's  seventh  type  is  as  follows: 

*(6)  7»  A  still  more  unusual  type  is  seen  in  the  performance 
of  the  righting  action  without  attachment  of  the  tube  feet  of 
any  of  the  rays*     Preyer  (1886)  and  Romanes   (1885)  have  given 
account  of  certain  ways  in  which  this  is  sometimes  accomplished* 
The  typical  tsethod  seems  for  the  starfish  to  raise  its  disk 
&igh  standing  on  the   tips  of  all   the  five  rays,    then  to  swing 
one  or  more  rays  over,  or  one  or  more  under  or  both  until   the 
body  topples  over  ventral  side  down*     In  my  own  observations, 
the  righting  without  attaching  the   tube  feet  was  seen  only  when 
these  were  experimentally  prevented  from  taking  hold*     The 
starfish  then  writhed  and  squirmed  irregularly,    taking  various 


trf*    flL. 


-67  • 

bizarre  forms,  until  it  had  succeeded  in  getting  its  ventral 
side  down^when.the  squirming  ce«sed, 

The  method  of  righting,   described  by  Romanes  and  Preyer 

e,c£ 

seems  to  be  confined   to  Astropfroien  and  its  allies.     I  hav» 
never  had  access  to  one  of  these  species  and   therefore  shall 
regard  this  highly  specialised  sand  burrowing  group  as  outside 
the  scope  of  the  present  paper*     The  peculiarities  of  their 
righting  reaction  are  said   (Romanes  188$)   to  be  contingent  upon 
the  fact  that  the  tube  feet  are  not  equipped  with  suckers  and 
hence  do  not  attach* 

Description  ££  the  riiditimt  reaction  as  ±±  oosurs   yhen  the 
tube  feet  are  prevented  attaching  by  inverting  the  animal  o* 
sand. 

With  the  animals  at  my  disposal  it  was  thought  possible  to 
prevent  the  attachment  of  the  tube  feat*' by  investing  upon  sand. 

2he  behavior  of  a  large  sluggish  Pitas ter  .when  inverted 
on  earn   is  interesting  in  connection  with  Moors   (1916,  1918, 
1920#  19204)  recent  observations  on  strychnine  poisoned  starfish* 
The  tube  feet  at  the  tips  of  all  of  the  rays  of  the  large  sluggish 
animal* I  had  under  observation  extended  out  toward  the   tips  and 
the  rays  bent  dorsally,   setting  themselves  more  nearly  at  right 
angles  to  the  actively  extended  tube  feet*     The  tube  feet 
however  did  not  attach  as  they  came  in  contact  only  with  sand* 
The  coordination  of  tube  feet  did  not  spread  back  very  far  and 
the  dor so -flexion  involved  only  the  distal  pa»ts  of  the  rays* 
Tor  some  time  all  five  rays  remained  donro-flexed*     'tfhen  the  animals 
•we*-  placed  on  1t$s  ventral   side  on  the  sand,    there  was  still  ?very 
marked   tendency  for  the  rays  to  «11  bend  dorsally  at  the  tips* 

Now    hen  a  similar  specimen,   large  and  sluggish,  was  placed 
in  a  dish  of  strychnine  sulfate  in  sea  water  1*10,000  the  same 
picture  appeared,  with  the  additional  factor   t  at  the  tube  feet 
suckers  were  so  paraliaed   that  they  could  not  attach  to  a  solid 
substrate*     There  was  then,  a   tendency  toward  dorsoflexion  at 
the  tip  of  the  rays  and  a  failure  of  the  coordinated  impulse  to 
spread  readily  among  the  tube  feet  as  a  result  eiffi.r    -f   the  paralys* 
of  the  tube  feet  by  strychnine  and  of  prevention  of  their  attachment 
on  sand* 

These  results  are  probably  merely  analygous   to   those  of  Moore 
on  As ten. an  forbeai  and  tend  to  demonstrate  the  many  ways  in  which 
a  givoii  response  may  be  brought  about  in  the  various  pxx  represen- 
tatives of   the  asteroidea.     I  have,   moreover,   so  far  been  unable 
to  get  in  yisaster   the  marked  dorao-flexion  which  Moore  figures 
for  Aateria  lesi. 


WMfiM 


4&  q»i*y  fl'toriftl  i         ^ypflft^  i^H 

J£*£LLIL: 

.    XJB9C; 

.i^. ".»•*.  aetfr  aai41tffTiil  vtf'- 


.-.  iiii  A    •mftBA:' 


- 
X^*^nf 

, 


i 


&  > 
fc-x« 


-68- 

It  would  be  obviously  impossible  for  the  suckers  to  attach.,  yet  tha 
animals  (Asterina  especially)  righted  themselves  quite  as  neatly  as 
on  a  solid  substrate.  Pilaster,  however,  would  not  right  easily  un- 
less in  active  locomotion  at  the  time  of  inversion* 

A  specimen  actively  crawling  in  the  direction  of  a  e 
(fig.  16)  was  quickly  inverted  on  sand.  The  tube  feet,  which  were 
retracted  because  the  animal  was  lifted  from  the  substrate,  extended 
at  once  toward  a  e.  B  and  £  moved  up  orally  and  twisted  toward  a  e, 
0«  bent  up  and  over  the  disk  while  a  s-   twisted  toward  each  other  and 
the  tube  feet,  as  soon  as  they  came  in  contact  with  the  sand,  began 
executing  the  step  reflex.  Thus  each  ray  moved  so  as  to  set  itself 
more  nearly  at  right  angles  to  its  actively  extended  (Oriented)  tuba 
feat.  The  stepping  activity  of  the  tube  feet  on  a  a  resulted  in  their 
doubling  back  under  themselves,  so  that  the  tube  feet  were  striking 

<je 

out   toward   the  disk  instead  of  away  from  it    (see  raysAfig.   18,    19,   20). 
The  step  reflexes  of  the  tube  feet  in  contact  with  the  sand  were  very 
active,    the  ends  of  the  feet  plou^iing  back  through  the  sand  and  scat- 
tering the  grains  on  all  sides  to  a  distance  of  one  or  two  centimeters. 
The  movements   thus  initiated  continued  until   the  rays  a  e  had  walked 
back  under  the  disk  and  the  other  rays  had  moved  up  over  the  disk  far 

enough  to  overbalance  the  animal  and  complete  the  somersault.     Loco- 

'  '  -*   ^^^L^L^L^L^HI 

motion  then  continued  in  the  direction  of  a  e « 

The  righting  reaction  of  Asterina  on  sand  is  even  neata&r 
than  that  of  Pisastar.     This   is  dua  to  the  very  great  flexibility  of 
the  ray  tips  and  to  the  strength  and  size  of  the  large  disked   tube 
feet.     The  animal  rights  nearly  as  quickly  and  easily  as  on  a  solid 
substrata. 

INTJRPRKTATIOH  OJ  THJ  RIGHTING      REACTION  Aj^  A  PHASE 

OF  LOCOMOTION 
3Svide.no a   from  the  mo veme.nt  of  the   tube   feet   and  arms.. 


^srlftt** 


t?ew  Att 


BW 


u 

»ni/r, 

. 

• 

. 


-69- 

In  general   terms,    the  above  interpretation  is   that  the 
orienftlted   tube  feet  extend  out  in  the  direction  of  their  orientation 
and  in  this  state  are  ready  to   give   the  step  reflex  upon  contact  stim- 
ulation.     In  the  absence  of  such  contact  stimulation   there  are  reflex 
connections  between  the  myodermal  sheath  and  the  ambulaoral  nervous 
system  of  such  a  nature   that  the  ray,    by  twisting  or  bending  or  both 
sets  itself  more  nearly  at  right  angles  to   the  actively  oriented  tube 
feet.      Fig.    18  illustrates    the  first  movements  of  an  animal   inverted 
during  active  locomotion  toward  a  e.     All  of  the  extended  tube  feet 
are  protruded  in  the  direction  of  the  former  anterior.     Figs.. 19  aad 
20  illustrate   the  movements  of  the  arms  as  described  already    (p$  (,£  ) 
wttch  result  in  righting  and  in   the  ray  assuming  a  position  more  nearly 
at  right  angles  with  the  oriented   tube  feet.     During  the  righting  pro- 
cess the  un stimulated    tube  feet  remain  extended  toward  the  animal's 
anterior.     The  rays  a  e.   however,    in  accordance  with  the  above  princi- 
ple,   bend  toward  one  another  and  down  so   that  the  tube  feet  come  in 
contact  with  the  substrate,    execute   the  step  reflex  and  in  the  manner 
outlined  above  initiate  the  righting. 

The  tube  feet,   however,   have  been  regarded    (Romanes  and  Swart 
(1881),    Preyer    (1886),    Loeb    (1900),    Jennings    (1907),   Moore    (1910^1910^) 
Cole    (1913*  ))  as  taking  hold  of  the  substrate  and  pulling   the  animal 
over.     Observation  of   the  reaction  as  it  occurs  on  sand  show  that  this 
pulling  is  not  a  fundamental  or  necessary  part  of  righting.     Pulling 
by  oriented   tube  feet  is,   however,  a  part  of  the   step  reflex.     Since 
attachment  increases  with  the  resistance   to  the  step    (pp-<lft-),    and   th« 
resistance   to   the  step,    in  the  initiation  of   the  righting  reaction,    is 
very  great,    it  follows   that  attachment  is   tight  and  pulling  is   the  most 
noticable  activity  of  the  tube  feet.      It  is   this  pulling,    that  has  ob- 
scured  the  eyes  of  observers,    the  more  important  and  fundamental  thing, 
of  which   this   pulling   is  merely  a  part,    namely   the  step  reflex. 


•cfi/J    5e. 


. 

• 


•  . 


'  -  •  .    •. 


fltj^UABP 

'£    fi.?  t 


. 


-69a- 


If  then  the  righting  movements  of  the  aims  are  dependent 
upon  the  initial  stages  of  the  step  reflex   (oriented   tube  feet) 
and   the  rioting  movements  of  the   tube  feet  are  slightly  modified 
step  reflexes,   righting  is  itcelf  a  phase  of  loooraotion. 


.    - 

T'LA^it 

••••V-j    i^Afd 


t 


'irVU, 


•70- 
from  the  faot  that  the  stimulation  o£  tha  doreal 


myodermal  sheath  of  the  ray  JLj;  not  an  essential   factor  In  the 
reaction* 

If  the  righting  reaction  is  simply  a  modification  of  ordin- 
ary locomotion,   it  -would  be  expected  first  that  contact  stimulations 
on  the  doraal  myodarmal  sheath  of  the  ray  do  not  play  an  essential 
part  in  the  ordinary  locomotion  and  second,    that,    since  the  looomotor 
impulse  persists  in  a  given  direction  for  some  length  of  time,    the 
righting  reaction  in  the  locomotor  specimen  shows  a  direction  which 
is  very  closely  correlated  with  locomotion  before  and  after  righting. 
Several  laige  active  starfish  were  picked  up  when  in  rapid 
locomotion   and  balanced  inverted  with  the  central  part  cf  their  disks 
resting  upon  the  bottom  of  a  snail  inverted  beaker.      Care  was  taken 
in  the  manipulation   to  touch  only   trie  disk  and  not  to  remove  the 
animals  from  the  water  or  subject  them  to  any  other  unnecessary  stim- 
ulation*    In  evary  case  two  or  more  of  the  rays  started  to  bend  down 
(dorsally)  while  the  rays  on  the  opposite  side  began  to  bend  up*     The 
latter  movements  were  more  rapid   than  the  former  and  the  starfish  coon 
overbalanced  and  fell  off  the   beaker*     This  was  repeated  so  many  tiates 
that  there  is  no  doubt  in  my  mind  that  the  dorsoflexion  and  ventre- 
flexion  results  of  the  operation  of  the  "unified  impulse"  persisting  /  t 
from   the  locomotion*     That  these  movements  are  homologous  with  the 
early  righting  movements   (Jennings  type  1)  is  indicated  by  the  fact 
that  the  rays  which  turn  down  turn  also,   usually,    toward   each  other*# 


#  This  conclusion  is  rendered  more  probable  by  the  fact  that 
some  of  the  neurotomized  starfish  when  coordinated  in  locomotion 
would  show  righting  movements  if  inverted  quickly  and  gently*     These 
movements  were  similar  in  direction  to  those  of  the  normal  animal 
but  were  complicated  by  the  fact  that  sooner  or  later  these  animals 
tended  to   take  the  "tulip  form".      (Romanes  and  £wart  1881).      In  a 
few  cases   they  righted  themselves  quite  promptly. 


•    : 


' 


pi'  be. 


M^MMMMM»«w*«iW**««M*MMM«VW*<*>M'**«|Mj 

irivnfvR  e 

>LU9 

' 


-71- 

Moore    (1920)    states   that  if  suspended  with  the  ventral   side 
down,   an  Aateriae  forbesi  -will  remain  motionless  in  a  state  of 
ventral  flexure   indefinitely.     This  while  not  absolutely  tru«  of  an 
active  Pisaater  especially  at  first,    and  very  far  from  tjue  of  an 
active  Pyono podia,   may  be  said  to  describe  the     behavior  of  th«  more 
inactive  specimens  that  I  h>ve  tried  the  experiment  upon.     Moore 
says,    furthermore,    that   if  the  dorsal  wall  of  a  ray  of  such  a   sus- 
pended  specimen  be  irritated  by  rubbing  it  with  a  glass   rod,    the 
ray  will   flex  dor sally.      I  have  confirmed   this.     Moore,   however, 
neglects   to  mention  a   fact,    first  observed   by  Romanes  and  Swart   (1881) 
that  the   tube  feet  of  such  a    ray  whose  dorsal  dermis   is  irritated 
increase  in  activity.     The  normal  orientation  of  tube  feet  on  an 
active  but  unoriented  speoiraan  is  toward   the  tip  of  the  ray.      It  would 
seem  then  that  the  dorsal   flexure  is  due   to   the  principle  that  a  ray 
tends   to    set  itself  more  nearly  at  right  angles   to    the  actively  or- 
iented tube  feet*      This  is  perhaps  the  more  acceptable  as  a  point 
of  view  since  the  activity  of  the  tube  feet  has  been  observed  to 
spread  to   the  tube   feet  of  other  rays  and  to  be   followed  by  dorsal 
movements  or  lateral  twistings  of  these  other  rays. 

Moore  comes  to    the  conclusion  from  these  and  similar  ex- 
periments  that  the  dorsal  flexures  of  the  rays  which  he  has 

' 
elicited  by  contact  stimulations  are  the  separate  parts  of  the 

righting  reaction.     Aside  from  the  fact  that  the  righting  reaction 
has  been  observed   to   start  without  any  contact  stimulation  of  the 
rays,   my  observations  and   the   statements  available  in   the  literature 
have  led  me  to   the  conclusion   that  lateral   twistings  of  the  rays 
are  muoh  more   important  in  the   righting  reaction   (save   that  of 
otsn)      than  are  me^e  dorsal  flexures. 

Evidence  from  the   persistence  ojf  ffle   ** uni f i ed  iflipul s e " 


•72- 

It  remains  now  to   inquire  into   the  correlation  bet-veon  the 
direction  of  righting  and   that  of  locomotion  before  and  after  the 
reaction*      Sole   (1913<)  has  presented   some  evidence  on  this  point,   from 
•which  he  draws  negative  conclusions*     Hia  analysis  of  the  data  is,    I 
think,    incomplete  and   the  data  are  not  statistically  representative* 

He  argues  as  follows* 

"In  table  4  are  shown  the  results  of  a  number  of  tests  to 
determine  what  relation  exists  betwean  the  arms  used   in  righting  when 
the  starfish  is  placed  on  its  aboral  surface  and  the  direction  of  lo- 
oomotion  previous  to  and  subsequent  to   thy  righting  reaction*     The 
data  nay  be  summarized  ap  follows* 

Arms  e     ed     d  de  e     ea     a  ab  b      JPQ 

Crawling  previous   to   test  2     6       5     1                    3  2 

used   in  righting                                           S  2     16           1  2 

crawling  subsequently  2951                   2  3 

This  shows  that  whereas   the  four  spec i meats  used  in  these  taste 
righted   theasdlvae  on  arms  a  a  sixteen  out  of  twenty-four  times,    they 
had  been  in  nearly  all  cases  crawling  in  a  direction  nearly  opposed 
to  these  arms,   and  mo  reovor  they   continued  locomotion  in  the  same 
general  direction  after  righting  themselves.     An  examination  of  the 
individual  records   reveals   the  same  relations  in  a  great  majority  of 
cages** 

Itelow  is  table  4  to  which  column  2  and  column  5  have  been 
added  to  help  in  interpreting  the  data*     Cole's  studies  have  led 
him  to  the  conclusion  that  the  starfish  studied  crawls  with  £  anter- 
ior,  more  than  with  any  other  rays  anterior*     Unfortunately,  however, 
in   thasa  experiments  he  chose  animals  that  were  not   typical  in  this 
respect,    since  in  no   trials  were  they  crawling  toward  &   and  in  all 
but  four  trials  were  crawling  in  a  vary  different  direction*     Thit  in 
connection  with  the  fact  that  only  four  specimens  were  used,   all 
presenting  an  unusual 


•  :  •:  ^  &'i    JS0££4X 

' 

vo 

«•*    IK  30 


ftv«*Jr.»3     .      «anri»  no  0rr  leant 


>,•.•  tc  it  001061        8  ni  ^niv0*ro   ae.- 
oiU   r.i  nollQBOooX  teuntfnoe  v.orfj  le 

• 


to*  S  omloe  riciiiv  o*  *  »Xtf0»r  t 


^furr»llib  X"-1'   ^  ai  lallvjrco  *rer 


•Table  4* 

Relation  of  arms  used  in  frighting  to  direction  of 
previous  and  subsequent  crawling* 


Individual  Previously  Anas  used  Shift  of     Subsequently 

crawling  in  physiolo-     crawled 

,4  After  tri-il  anterior     righting  anterior 

"anterior" 
(rays) 


4  After   trial  50, 

d 

ea 

.0     efore     "         1 

•- 

ea 

i  After       "       10,; 

a 

e(b) 

,0  After     "         i,}-. 

0 

i{ab) 

,0  After       "       28^ 

od 

Ml 

,0  following  day 

•- 

Od 

n                    ft 

bo 

bo 

0         "                " 

a 

od 

.2  Trial  1 

PI* 

bo 

.2        "        2 

a 

Hi 

2,        "        3 

if 

ea 

,2        "        4 

od 

a* 

.2        "        5 

e 

M 

.4*1 

.. 

• 

A        M        2 

d 

JU 

.4         «         3 

d 

3l 

.4        w       4 

od 

•a 

.4                5 

od 

M 

.4                 6 

od 

ea 

.4                7 

d 

•a 

.4                8 

d 

ea 

.4                9 

od 

od 

.•                10 

— 

ea 

L4                11 

bo 

1.5 


Sfcift  of 

anterior 
from  "pre- 
viously 
crawling" 
(rays) 


1.5 

•«• 

•• 

—  — 

0 

«• 

1 

od 

2.5 

2 

bo 

.5 

2 

od 

0 

•- 

be 

.. 

0 

a 

1.5 

2.5 

ft  d 

2 

•• 

a 

—  — 

.5 

de 

1.5 

1 

M 

1 

2 

o 

.5 

2.5 

od 

.5 

— 

d 

•»•» 

1.5 

d 

0 

1.5 

od 

.5 

% 

od 

0 

2 

od 

0 

2 

d 

.5 

1.5 

d 

0 

1.5 

od 

.5 

0 

stationary 

«•>• 

•• 

bo 

mm 

.7 


These   trials  were  of  a  series  of  490  showing  the  persistence  of  the 
Biological  anterior  in  a  general  direction,   which  tends  to  rotate 
>wly  to  the  ri^it  or  the  left. 


-74* 

direction  of  loco-action,   Iea4a  DM  to  believe  that  the  data 
not  a  good  foundation  for  any  fusion,     Koreover  the 

tU*y  do 
conclusion  Hr-doeo  indicate  is  not  that  drawn  by  Cole. 

As  »0en  from  an  exanimtirn  of  column  5,    the  17   records  show 
that  tJie  Physiological  anterior  has  shifted  in  one  direction  or  the 
other  ^naveraee  of  seven  tenths  of  an  inter  radius,   per  reaction* 
Coles  conclusion  on  this  point,   as  seen  above  ie  that  "they^fbc  *Ja *$'* 
continued  tc  crawl,   in  the  same  general  flireotion  (an  they  did 
Before)  after  righting  themselves.* 

:-3oYorf    as  seen  from  an  examination  of  column  3,    the 
19  records  show  an  averse  athlft  of  anterior  (referring  to  th« 
rays  used  to  right  as  anterior)  of  1»5  inter  radii  per  reaction* 
Coles  conclusion  on  this  point,  however  ia  that  the  animals  right 
in  a  direction  nearly  opp+Bite  to   that  in  which  they  were  pre- 
viously (and  subsequently)  crawling.     But  the  arithmetical 
difference  between  theae  averages  of  data   (1*5  -  «7*  .8)  is 
•8  of  an  interradius  a  shift  which  is  approximately  equal   to 
the  shift  (,7  interradius)  which  Cole  regards  ae  no  shift  at 
all.     Obviously,    then  a  detailed  examination  of  Ooles  data  does 
not  ce-nfizta  |ii«  conolueiona* 

with  an  idea  of  clearing  up   the  relationship  between  the 
physiological  anterior  and  the  arms  used  In  righting  seventy* 
five  experiments  were  made  with  twenty-six  0  tar  fish  (20 
Pisaatar  and  6  Aaterjna.)*       The  starfish  used  were  in  active 
locomotion,  except  in  case  of  some  ef  the  Asterina  as  shown  in 
the  record,     manipulation  WAS  as  gentle  as  possible,    the  animal 
bein  ?  picked  up  by  the  disk  and  inverted  qulokly  without,   in 
meat  eases,   lifting  it  above  the  surface  of  the  water* 
Directive  factors  in  the  surroundings  such  .as  light  or  areas  of 
shaddew  etc*,  were  excluded  by  rotating  the  animal  in  successive 
trials. 


Relation  of  arms  ueed  in  righting* to  direction 
of  previous  and  subeoqusnt 


idividvnl.   Direction    Arms     Shift     Arms  Arms         Shift     Direction  Shift 

before     first    of         bent  ri.jhted     of          after           of 

inrrtina^   bent     anterior   up  on           anterior  rioting  anterio 

down,  in  radii  ventrally.  inradtt  in  radii 

.wan  11234  567                    8 


>.l  Hs  • 

aster          ,e 

aed 

0.0 

bo 

ed 

1.0 

•3 

0.5 

2                     ae 

aeb 

0.0 

ed 

e 

0.5 

ed 

1.0 

2                      'io 

aeb 

0.0 

bo 

ab 

1.0 

ae 

0.0 

1                     de 

e 

0,5 

(a)  bod 

Ja)e 

1.0 

ae 

1.0 

1                     e 

o  (e) 

0.5 

— 

ae 

0.5 

ae 

0.5 

2                     de 

dea 

0.0 

bo 

d 

0.5 

od 

1.0 

4 

(i)b>jfi 

0.0 

bo 

... 

.. 

.. 

.. 

5                     de 

•io(o) 

0.0 

bo 

de 

OP 

ae 

1.0 

5                    e 

rjg  (d) 

0.5 

bo 

a  (d)e 

0.5 

e 

0.0 

6                      ?.  1 

a(b}de 

1.0 

o(b) 

de 

1.0 

d 

1.5 

5                      o 

bo 

0.5 

a 

bo 

0.5 

bo 

0.5 

5     n                b 

bo 

0.5 

dea 

be 

0.5 

0 

1.0 

5     "                 tf 

eda 

1.0 

bc(d) 

ae 

0.0 

ae 

GL.O 

7                     e 

1C 

0.0 

toe* 

ea 

0.5 

ea 

0.5 

8                      bo 

(b)ctfd 

0,0 

(b)sit 

•d 

1.0 

cd 

1.0 

8                     de 

de 

0.0 

.. 

de 

0.0 

d 

0.5 

7                      od 

b 

1.5 

a  ode 

b 

1.5 

b 

1.5 

5                      de 

de(o) 

0.0 

boa 

M 

0.0 

de 

0.0 

7                     ae 

e(a)b 

0.0 

(b)od 

ae 

0.0 

•  a 

0.0 

5                     p 

(b)ae 

0.5 

bo 

ae 

0.5 

.. 

-• 

9                      ae 

abod(e) 

.. 

e 

ab 

2,0 

stopped 

•• 

9                      de 

(u)do 

1.0 

ebo 

d»  a 

1.0 

ae 

1.0 

10  *                bo 

bo(a) 

0.0 

•V  •» 

... 

... 

-- 

— 

11 

bo 

be 

0.0 

ade 

bo 

OP 

bo 

00 

1  7 

Od 

od 

0.0 

abe 

od 

0.0 

.. 

»» 

12 

de 

(a)ed 

0.0 

bo 

ed 

0.0 

ed 

0*0 

13 

(•a  bod) 

0.0 

(abode) 

.. 

•  - 

*» 

.. 

12 

od 

deo 

1.0 

ab 

do 

1.0 

de 

1.0 

12 

de 

(a)de 

0.0 

bo 

a  ,> 

1.0 

e 

0.5 

12 

de 

e(a*)a 

1.0 

bod 

M 

1.0 

jj. 

1.0 

12 

2  . 

ed 

1.0 

ab 

ed 

1.0 

ed 

1.0 

14 

0 

da  o 

O.D 

aed 

do 

0,5 

e 

0.0 

15 

4 

(o) 

0.0 

tulip  form  — 

e* 

-- 

•• 

16 

od 

a 

2.5 

(e)  (a)bo< 

i  if 

2.0 

Ml 

2.0 

16 

ae 

ae 

0.0 

bod 

1,J 

o.c 

aa 

0.0 

16 

If 

ed 

1.0 

cba 

ed 

1.0 

li'j 

2.0 

16 

ab 

ae 

1.0 

od(e)b 

a4 

1.0 

1.0 

16 

ae 

ao 

0.0 

bod 

ae 

0.0 

ae 

0.0 

17 

bo 

bo 

0.0 

aed 

bo 

0.0 

tto 

0.0 

17 

bo 

bo 

0.0 

aed 

bo 

0.0 

bo 

0.0 

17 

bo 

bo 

0.0 

aed 

bo 

0.0 

bo 

0.0 

18 

od 

bo 

1.0 

aed 

bo 

1.0 

od 

0.0      ^ 

19, 
19 

d 

•J 

abode 
abode 

«- 

(dea) 

e 

bo 
bo 

1.5 
1.0 

od 
(b)od 

ilo 

19                     Od 

abode*  (f) 

.. 

• 

bo 

1.0 

0 

0.5 

• 


. 

. 


)60 

JMM 


46  No.  20  Aster-     ae 
ina 
47  "     20        "            ab 

ae(b) 

0.0     dob 
1.0     abo 

ae 

TO 

0.0 
1.0 

^topped            •- 
ab                      0.0 

48   "     20 

n 

de 

(de)abo  O.o     ao(b) 

de 

0.0 

^e                       0.0 

49   "      20 

* 

ae 

ae 

0.0      bou 

M 

0.0 

-"3                                   0.0 

50  "     20 

H 

0 

0 

0*0     abod 

o 

0.0 

stopped 

51   "     20 

i 

ea 

ea(bo) 

0.0     dbo 

a  -i 

0.0 

ea                      0.0 

52  »      20 

A 

de 

(d)ea 

O.C     bod 

ea 

1.0 

od                      1.0 

Si   "      20 

H 

0 

o 

0.0     tulip 

form 

mm 

—                    .. 

54   "      20 

14 

d 

d 

0.0     (de) 

de 

0.5 

stopped           •- 

55 

21 

ae 

ae 

0,0      — 

od 

2.0 

de                      1.0 

56 

a 

bo 

be 

0.0     aed 

bo 

0.0 

stopped 

57 

21 

da 

abode 

stopped 

.. 

mm 

--                  -- 

58 

23 

se 

ae 

0.0     stopped           —                 -- 

59 
60 

23 

24 

n 

a         a(e) 
0(Bta)abode 

0.0     bod 
stopped 

M 

0.5 

stepped            — 

61 

24 

N 

de 

to 

tulip  fora 

mm 

— 

.. 

62 

24 

n 

de 

00 

2.0     ade 

bo 

2.0 

stopped 

63 

25 

n 

bo 

bo 

0.0     ade 

bo 

0.0 

stopped 

64 

26 

* 

ab 

Ml 

1.0     bod 

ae 

1.0 

*                       .- 

65 

25 

* 

Bo 

bo 

0.0     ade 

bo 

0.0 

-- 

66 

25 

H 

ae 

ae 

0,0     bod 

ae 

0.0 

mm 

67 

M 

M 

ab 

MJ 

1.0     bod 

ae 

1.0 

mm 

68 

26 

N 

de 

eaod 

1.0     Tarn. 

e 

0,5 

mm 

69 

23 

H 

3 

de 

0.5     dob 

it 

0.5 

mm 

70 

22 

N 

de 

de 

0.0     oab 

de 

0.0 

mm 

71 

23 

M 

ab 

ae 

1.0     odb 

ae 

1.0 

*                                       -- 

Tl 

25 

©Stationary 

rigid 

tulip   form 

73 

24 

* 

n 

« 

* 

* 

* 

74 

25 

H 

* 

1 

• 

M 

* 

75   n     24 

H 

N 

• 

M 

* 

I 

•  36 
(64  trials) 


.6 
(62  trials) 


.57 
(44  trials] 


-75- 


Records  were  taken  (column  1.)  of  the  direction  of  locomotion 
before  righting  and   (eoluon  2)   tha  a  IMS  that,   after  in  verting, 
thf  animal,    first  twisted  and  bent  down  tow-rd  the  substrate* 
These  two  findings  were  compared  in  each  experiment  and  the  shift 
in  either  direction  of  the  leading  rays  or  "physiological  anterior" 
set  down  in  oolumn  3*       The  turning  down  of  certain  rays  is 
usually  followed   (  rscpac  or  preceded   )  by  a  lifting  up  of  others* 
The  rays  that  lifted  up  free  of  the  substrate  **  but  not  those 
that  were  oriented  on  the  substrate,   in  the  way  described  ibova, 
to  walk  over  the  initiating  rays*  were  next  recorded   (column  4). 

The  ray  a  that  turned  down  -were  not,   always,  of  course  the 
same  is  those  that  the  animal  uaea  ia  righting*     ihese  latter 
are  listed  in  ooluran  5,   and   the  shift  of  anterior  from  the 
direction  bef  re  inverting  to  the  araa  used  in  righting  is 
listed  in  column  six*     The  anterior  after  righting  is  listed  in 
column  7  and  its  shift  from  the  direction  before  inverting  is 
listed  in  column  8.         Blue  the  shifts  of  anterior,  listed  in 
columns  3,6  and  8  refer  to   the  original  anterior  before  inverting* 

A  comparison  of  the  averages  obtained  here*  and  those  drawn 

from  Colt'a  data  shows  that  careful  manipulation  of  the  starfish 

e. 
and  the  use  of  a  lirge  number  of  individuals  riduces  the  shift 

of  anterior  considerably.     .\s  shown  by  the  rays  that  are  first 
turned  down,    the  anterior  at  the  beginning  of  righting  feas 
shifted  *38  of   in  inter-radius  on  an  average  of  64  observations* 
As  shown  by  the  rays  on  which  the  animal  rit#its)  the  anterior 
during  the  righting  reaction  has  shifted  *6  of  an  inter-radius  from 
where  it  was  before  the  animal  was  inverted.     After  righting,   the 
anterior  shifts  slightly  back  Coward  its     original  direction,  as 
shown  by  the  fact  that  the  average  shift  after  righting  is  less 
than  during  righting*     This  shows  more  markedly  in  the  average 


«e  a&J 


-76- 


drawn  from  Sole'w  table. 

This  return  of  the  anterior  to'*ard  its  original  direoticn 
ia  an  example  of  the  tendency  which  we  lave  noticed  in  connec- 
tion with  the  deviation  reaction  (  p»  iff  )  for  the  coordinated 
impulse  to  return  to  its  original  direction,  even  after  having 
been  actively  oriented  in  aoue  other  direction* 

le    (1913)  has  shown  very  conclusively  that  the  impulse 
to   locoraota,   in  the  starfish  tends  Iks  to  maintain  the  same 
general  direction,    from  trial  to   trial. (Between  each  trial   the 
animal  was  held  inverted  by  the  disk  until  the  raya  dropped  and 
then  "started"  on  the  bottom  of  an  aquarium  in  a  non-directive 
chamber.).     Hie  tendency  to  lK*ep  in  the  sans  direction  was  of 
course  only  general,   aa  there  wag  also  a  rotation  of  the  anterior 
toward  the  rifc-Ut  or  toward  the   left,   and  certain  aberrant 

deviations,  of  from  one  half  to   two  and  a  half  inter-radii 

i#u/n£ 

Incurring  quite  frequently.       In  B    eoanafrting  up  these  deviations 

Lu&) 

from  the  table  opposite  £•  It      it  was  found  that  they  amounted 
to  a  sum  total  of  217  intor-rudii  in  499  trials*     'Ihis  amounts  to 
a  shift  of  anterior  of  .43  inter-radii  per  trial  which  is  quite 
comparable  quantitatively  with  the  figures  (,38  ,«CO, .67/  inter- 
radii  ^obtained  from  the  status  of  the  direction  of  the  coordinated 
impulse   ttiroughout  the  righting  reaction* 

Z  conclude  therefore  that  righting  it  an  aspect  of  locomotion* 


I/  jriaas.tar  ooraceus     presents    Uu   three  follo^in^  well 
marked   physiologic*!  spates    (1)    "Rigid"      (L)    "loconiotor"      (3) 
"active   but  unorientod*        i'he   responses   of   th-i   tutu   feet,  and 
arms  differ  markedly  according  to    tha  physiological   state  of 
the  animal       Other  starfish  studied  present  analogous   states* 

2/  intension  of  t  ,e  tuba  feet  depends  upon  the  proper 
physiological  st^te   and   absence  o<    stimuli  which  cause   Detraction. 

An  isolated   tuba   foot,    infl-itod   -*ith  watar  und  ir  pressure  can 

/ 

b3   caused   to   glonrly  oxtend;   but  not   rjuite  normally, 

•r? 

3/  At^ching  is  condition-^    by  the  proper    uTysiolo»?ioal 


state.     An  isolatyl    tu  :>B   foot,    properly  prap^rud  and   i 
with  vfat^1"   is  rnora  apt   to  a  -taoh   if   taken   frota  i   ri^id   starfish 
than   from  a  loooiaotor  stirfisn.     Attaching  may   involve  only  a 
part   of  the   ainbulaoral   digk. 

4/  .Uth'lr?nralAis  a   response   to  cont-iot  stimulation,    as  is 
dotaohing,    under  certain  oon^  itions» 

I/  Th«  step  '-eflex  intargrades  ^ith  the  withdrawal  response 
as  elicited  by  10  ivict  stimulation  of  the  ambulacral  disk*  It 
is  da  ;'md3nt  upon  tirs  contact  stimulation  uvl  .t.^e  presence  of 

the  locoiootor  irapulsefc  vhioh  orients  the  ?tep  reflex  and  conditions 

» 

the   tube   foot  to   b-3   rigid  and   support  animal  during  loootnotion* 
The   tu>>e    foot  is   attached  most   strongly  during    the   first   part  of 
the   step  raflox*      The  tube   foot  is  a    tachad  *ivh  2.8    (A.g  farina.) 
or  ii,06   (ryono  podia)      times  as  much  force  as  it  exerts  in  pulling 
against   resistance*      ITii^  facto/I-  is    relatively  constant   for  vrious 
values  of   the   resistance.      'm&   strorvjth  of   the   step   reflex 


varies  markedly  with  diff3;r3nt   spscias* 

»/Joordin-tion  of  thj  'tuDa  fjet  of  ti;e  rigid   starfish,    like 


tint  of  tha   gills,    is  u   siiaple   apreid  of  exuension  or  rat^ction. 
It  ia   ref   rabla  hypo  the  tioally  to  a   simple  rwrv3   rut. 


(*) 

to  «. 


-79- 

7/  Coordination   in  the   active   but  unoriented   starfish  involves 
orientation  of  tne  distal  tube  feet,    toward  the   tips   of   the 
rays.      With  the   rays  on   separate   substrates,    thi-  -jncy 

results    in   their  -valuing  in   five  dif  fe^snt  directions,      ^nder 
pathological    conditions   this    ten  enoy  results   in  autotumy. 
Orientation  of   the   tuoe   feet   is   not   referable    to  a    simple   nerve 
net   as   is   Coordination   in  extension  and    -et-action  but   to  a  more 

complicated   and    possibly  an   independent  mechanism. 

>L^ 

8/  The  unified    impulse   is   formed    (1)   "by   the   spreading  bink  of 
the   oriented   stale   in  tne   tip  of  one   of  the   r^ys.    Various   factors 
may  cause   tne   relative   increase  'vhi.Cn   results   in  its   spread  over 
t.ie   rast  of  t   e  animal      (2)    by   the   spreading   baoV  and   fusion  of 
Reoriented   states   in  adjacent   rays.      (3)   By  direct  orientation 
of   tne   tuba   feet   from  exits,  tion  of  the  dermal  nerve  n;t  or  the 
tube   feat,    themselves* 

9/  .Behavior  of   the   oriented  animal   is  conditioned   by  all  of 
the  above  factors  acting  at   the  same   time  and  in  nice    balance 
against  each  other.      In  the  actively  migr*ting  starfish  the  tube 
feet  are   all   oriented   in   tii3    same  direction. 

10/  The  unified    impulse^;  (l)    in  some  types  of   righting  reaction, 

(2)  in  the    Deviation   reaction,    (3)    in  the  looomotor  starfish  with 

— **s. 
a   curved  lateral   arm,    is   broken  up   into   areas  in  Wjiioh  the  tube   feet 

are   oriented    in  different  directions.     This   is  highly  adaptive.  A 
possible    -hysiolosical  explanation  is   saen   in   th3   traction  on  the 
tube   feat  resulting    irom   the  movement  of  the   rays  over  the  sub- 
strate. Evidence   for  tuis  hypothesis  is    -rawn  from    (1)  Ueurotoraized 
starfish      (2)    starfish  wit,,   the  rays   placed  on  separate   substrates; 

(3)  the  mechanics   of   the  deviation   reaction. 

ll/  The   righting  reaction   is  a  phase   of  ordinary  locomotion 


so 

with  the   starfish  in  more  or  less  a    state   of  unifi-d   coordination 
The  movements  of  the   arms  are  explained  on   the  assumption  of  re- 
flex connections  by  '#hich  the   arms  a^e   bent   or  twisted  more  nearly 
at   right   angles   to   the   -actively  oriented   tube   feet*      Evidence   for 
this  conclusion   is  n  ra*?n    (l)    from  the  movements  of  tha   tube   feet 
md  arms:    (2)    from  an  analysis   of   tne   reaction  -*hen   the   tube   feet 


are  proventsd  .attaching  by  inv'irtin^   the   Animal  on   sand;       (3) 
from  the    fact   th  >t   stimulation  of  the  dorsal  myodermal   sheath  of 
tn3   ray   is  not    ->.n  essential    factor   in  the   rig;  ting  reaction    (4) 
from   the   fact   tnat   the   "unified   impulse"   persists  during   the   ri   ht- 
ing   reacti  .n  in  Uie   saiae  direction   to  a  decree   quantitatively  com- 
parable   to   its    persistence   in  ordinary  locomotion   (Cole). 


Baudelot,    :ai. 

x 

1872.     Ktudes  general es  sur  la  Systeme  Nervaux. 

Aroh.    Zool.    ixper.    et  Geti.,    1,    177-216. 
Bohn,    G. 

1908.     Las  asaais  et  lee  erreurs  cheat,  lea  etoiles  de  mer  at 

las  ophiures.     Bull  Inst.   Gen,   Psych.,   8,    21-102   , 

T~ 

56  fig*,  in  text. 
Botazzi,  F. 

1898.  Contributions  to  the  physiology  of  unstriated  muscu- 
lar tissue.  IV.  Jour.  Physiol.,  22,  481-505,  (p.  501  ff.), 

^-u- 

22  figs,  in  text. 
Clark,  H.  L. 

1899.  Synaptas  of  the  New  England  Coast*  Bull.  U.  3.  Fish. 
Cornm.,  19,  21-31,  2  pis. 

**v*. 

Cole,  L.  J. 

1913a.   Direction  of  locomotion  in   the  starfish  (Aeterias 

fprbeaiJJ.iSxp.   Zool.,    14,    1-32,    5   tables,    9   figs,    in  text, 

*  -*-*t_ 

19l3b.  iSrperimants  on  coordination  and  righting  in  the  star- 
fish.    Biol.   Bull.,    24^    362-369,    2   figs,    in  text. 
,    R.   P. 

1909i.   Preliminary  Deport  on  the  behavior  of  Schinoderms. 
AJB.  Kept*  Director  Dept,  Marina  Biol,,  Year  Book, 
(Jarnegia  Inst.,  vVaeh.,   8,   128-129 

i  ^*^ 

1909b.    The  movement  of  tne  Starfish  ^oninaater   toward 

the  light.      Zool.   Anz.,    35,    193-195,    1   fig.    in   text. 

1911,  Reactions  tV  light  and  other  points  in  the  behavior 
of  the  starfish.  Pap.  Tortugas  lAb.  Carnegia  Inst., 
Wash.,  3,  95-110,  6  figs,  in  text. 


1914.  The  difference  of  white  and  black  walla  on  the 
direction  of  locomotion  in  the  starfish.  Jour. 
Anim.  Behavior.,  4,  380-382. 

•vK 

Cuenot,L. 

/ 

1888.      Contribution  a  1'iitude  anatomique  dee  Aste'rides. 
Aroh.  Xool.  Kxpe'r.    et  Gen     .,    Se'r.   2,    5,    Supt., 
mem  II,    1-144,   pi.   1-9. 
De  l^oore,    J.,    and  Chapeaux,   M. 

1891.      Contributions  a  la  physiologic  nerveuse  dee  achin- 
odarmes.    Tidsohr.   Jfedarl.   Diark  Ver.,    (2),    Deel.    3, 
1891,    108-169,    pi.    7. 
Driesoh,   H. 

1908.      Science  and  philosophy  of  the  organism.    (Aberdeen 

University)   2,   XVI    +  381  pp. 

/>\- 

Graber,    V. 

1885.      lieber  die  Helligkeits    -  und  Parbenempfindlichk«it 
einiger  Meerthiere,      S.B,  Akad  Wiss*  Wien  F.ath. 
Hat.   n.,91,abt.    I,    129-150,    35   tables. 
Grave,    C. 

1900.      Ophiura  brevispina.     Mem.   Hat.   Aoad,    Sol.,   3,    77-100 
pi.   1-3,    5   figs,    in   text .(F Mem.   3iol.  lab.   Johns 
Hopkins  Univ.,^No.   5. 
Greenwood,   li. 

1890*     On  the  action  of  nicotine  upon  certain  invertebrates 

J.       .   Physiol.,    11,    570-605, 
Hess,    C. 

1914.      Unterzuohung  ufber  dem  Lichtzinn  bei  Jcninodermen. 

Pflu^ger'a  Arch.,    160,    1-26,    6  figs,    in   text. 
Holmes,    3   .   J. 

1911,      The   evolution  of  animal   intelligence.    (New  York,    Holt), 
V<- 296  pp.,    18   figs,    in   text. 


• 


Jennings,   H.   S. 

1907.     Behavior  of  the  starfish  Aetarias  aertulifara 

Xantua*    (A.    forreri  Oe     Loriol).     Univ.   Calif, 

Publ,   Zool.   4,   53-185,    figs,   in   text. 
Krukenberg,    0*  Fr«  W» 

1881.     Betrage  zu  einer  Narvanphyaiologie  der  ^Quinodoraen. 

In  Verg.  Phya.   Studion  (Heidelberg,    Tarl  Winter's 

Buohverhdg. )  2  Reihe.   1  abth,   76-82,   2  figs,  in 

text. 
Loeb,   J. 

1900.      Comparative  pliyaiology  of  the  brain  and  comparative 

psychology,    (New  York,   Putnaa),  X     309  pp.,    39   figs. 

in  toxt. 

!,.,    ynd  liamam,    0. 
1899,     Seesterne  in  Bronn'a  Klasaen  and  Ordungen  da»  Thier- 

Reiohs.    (Leipzig,    C*   P.  Winter* *che  Buohverhandlung) 

2.  Abt.    3,    461-744,    pla.   1-12,   13  figs,    in  text. 
,  S* 
1908*     Studien  der  I'hyisiologie  des  WerveneyatonB  der  JSohino- 

dertnen,    X.  Die  Ifagsehen  der  Beentdrne  und  die 

Koordination  ihrer  Bewegun^en,  Pfluger's  Archir. ,  122, 

318-360,    14  figa.    in  text. 
ItfOSb     Studien  d0r  Phyeioldgie  dea  Herven»yatem»  der  /.ohino- 

darmen,   II,   Ueber  daa  Hervenoystem  der  Seeetarne  und 

uber  <T.en  Tonus.     Pflugere  Arohiv.  123,   1-39,   d  figa. 

•W^ 

in  text. 

1909a.   Sinne*  phyciologie     Studion  an  :,ohinodeTtr<jn.  Zeit. 
f.  Allg.   Physiiol,,    9,   112-140. 

V-V. 

1909b.   Studien  zur  Phyoiologie  dea  Uerverisyc tarns  der  '^ohino- 
d&rmen  III  Ueber  die  Armbewegung'^n  dsr  Schlangensterne 
und.  V*  Hexkull'a  IFundsuaentalgaaetz  fur  den    . 


, 


' 


verlauf,      Pflugers  Arcniv.,    126^    371-406,    6  figs. 

in  text  and  4  tables. 
llaet,    R.   0. 

1911.      Light  and  the  behavior  of  organisms.      (New  York, 

Wiley)   XI -I- 410  pp.,    3?   figs,    in   text, 
iieyer,   R. 

1906,      Unt :  rsuchung  uber  <?.en  feineren  Bau  des  Nerven  systems 

t c r  /•  s:  t <: •  r i <? en    ( AgteriaE   rubens ) . 

Zeit.   Vice.    Zool.,    £tt,    96-144,    plr.   9-1C. 
Moore,   A.  R. 

1910a.   On   the  riffrtinf;  movements  of  the   starfish.      Biol. 

.11.    14,    235-239,    1    fie.    in   text. 
l?10b.   On   the  nervous  mechanism  of  tha  righting  movemente  of 

the   starfish.      Araer.   J.   Physiol.,    27.    207-211,   2 

fign.    in   text. 
1916.      The  action  of  strychnine  on  certain  invertebrates 

J.   Phnn/i  and  Exp.    Therap.,    9,    167-169. 
.\917.      di3,acal   difforontiatior:   in   the  nervous   syetem  of 

invertebrates.      Proc.   Nat.    Aoart.    Sol,    3,    59B-602. 
1918,     ^Hav^r^al  of  reactions  by  means  of  strychnine   in 

plans riana   ^nd   starfish.   J,   Gen.   Physiol.  ^,    97-100, 

3  fiei a.   in  text. 
1920a     The  action  of  atryohnine   and  nicotine  on   the  neuro- 

musonlar  raschaniscj  of  Asjteria^s.    J.   Gen.   Phyaiol.,    2, 

201-204,    5   figs,    in  text, 
1920b     Steraotropism  as  a   function  of  neuromuscular 

organization.      ,    J.         Gan.   Phyaiol.,    2,    319-324,    4 

*VA^- 

figs*   in  text. 
Hori-oan,    '.".',   W, 

1900.     Do    the  reactions  of  the  lovor  -aniraalo  against  injury 
indicate  pain  senaationn.     Amor,   J.   Physiol.,    3, 
271-284. 


Parker,    G.   H. 

1919.     The  Elementary  Nervous  System.      (Philadelphia 

Lippincott)   229  pp.,    53  figs,   in  text. 
Plessner,    H. 

1913.      Untersuohen  ii«ber  den  Physiology  der  Seesterne. 
Zool.   Jarb.   Abt,    f.   Zool.,33,    361-386,    7   figs, 

'  AM- 

in  text. 
Preyer,  W. 

1886.  Ueber  die  Bewegungen  der  Seesteme.  Mit.  a.d. 

Zool.  Stat.  zu.  Heap.,  7,  27-127;  191-233,  pi.  7, 

>*^-i 

27  figa.  in  text. 
Prouho,  H. 

1890.  Du  Sens  de  1'Odorat  ohez.  les  e'toiles  de  msr. 
Gompt.  Rend.  Aoad.  Sciences,  Paris.,  110, 

•A-*-^-— CF 

1343-1346. 
Reamur,    R.  A.   P.    de 

1710,     Du  mouvement  progressive  et  de  quelqu^s  autres 

mouvements  de  di verses  espeoes  de  coquillages, 

orties,    et  ^toiles  de  mer.     Mem.  Acad.   Roy. 

Science  Paris,    17^0,    439-490,    PI.    9-12. 
Romanes,   G.   J.  and  Kwart  J.   G. 

1831.      Observations  on  the   locomotor  system  of  the 

jjJohinodermata.     Philos.    Trans.   Roy.    Soc.  Lon^. 

3^72,    Part   HI,    829-882,    pi.   79-85. 
Romanes,    G*   J. 

1883.      Observations  on  the  physiology  of  the   eohinodermata 

J.   Linn.    Soo.    17,    131-137. 
1885.     Jellyfish,    starfish,   and  sea-urchin.    (New  York. 

Appleton)XI  t  323  pp,  63  figs,  in  text. 


. 


rajs  ?b  ee  *»I   .xf-rfr  jf  ••  »n»l 


eb   •%   »  .  fUBM*A 

?   OD  Je  0T 

,5/i.--:,  t  :^    sc- 

.  .ir^l  ec reel 68 


. 


Rusao,    G. 

1913.  Analisi  e  mecoanismo  del   reflesso  di  raddrizzamento   e 
di  altri  raovimenti   ooordinati  negli  eohinodarmi. 
Atti.   aco.  Gioania  Catania,    Serie  5,    6  Mem.   22,    1-14, 

Seheinmetz,   P« 

1896.     How  do   starfish  open  Oysters  J.  Jiar*   Biol.  Ass..  4, 

/     *"• 

n.s.,    266-268,    9   figs,    in  text. 
Steiner 

1898.     Die  funktionen  des  Cent  talnervenays terns  und  if?  re 
Phylogenese  3,   Die   tfirbellosen  This  re,    (Braun- 
schweig    Priederioh  Vieweg)  X  *  154  pp.,   1  pi., 
46   figs,    in  text. 
Sterne,    0, 

1891.      Five  souls  with  but  a    single   thought,    the 

psychological  life  of  the  starfish,     luonist,  1 

•M- 

245-262,    6  figs,    in   text. 
Spix. 

1809*     Memoire  pour  servir  a  I'historire  de  l*Asterie 

•£3 
rouge,    etc.     Ann.  Mus.  Hist.  Nat.,   Paris,   438- 

A 

458  pi.    32-33. 

Tiedemann,    I< . 

1815.     Beobachtung  liber  das  Nervonsystem  und  des  sensibilen 
Brscheinungen  der  Seestame.Meokal's  Arch.f.   d. 
Physiol.,    1,    161-175. 

4V 

Verrill,   A.  S. 

1914.  Monograph  of  the  shallow  water  starfishes  of  the 
north  Pacific  coast  from  the  Arctic  Ocean  to   Calif- 
ornia.    Harriman  Alaska  Series  of  the  Smithsonian 
Institution  Publications.   14,   pl.l.,   XII  <- 408  pp. 


- 


. 


Von  Uexkuell,  J. 

1900.   Die  Physiologic  des  Seeigelatachela.   Zeit.  f. 

Biol.,  39,  73-112,  4  figa.  in  text. 
1903.   Studien  ueber  den  tonus  I.  Der  biologeaohe 

Bauplan  von  Sipunculua  nudus .  Seit  f,  Biol.,  4Jt, 

269-344,  pi.  6.  28  fige.  in  text. 
Vulpian,  A. 

1866.  Lecons  sur  la  physiologie  generale  et  oompare'e  du 

syatame  nerveux,  faites  au  Museum  d'hiatoire  naturelle 

(Paris.  Germer  Bailliere)  737-742. 


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